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Biomedical subjects

K L Alexander

Publications and source records attributed to K L Alexander.

12 recordsLinked to original sources

Spectacle-mounted prisms as an aid in face-down positioning after vitrectomy surgery.

PURPOSE: To report a modification in the design of bed spectacles to provide an aid for patients who undergo face-down positioning after vitrectomy with gas-fluid exchange and postoperative gas tamponade. METHODS: New equipment design. Bed spectacles that use prisms to move the image 90 degrees around the horizontal meridian were modified by rotating the prisms in the frame 180 degrees and adding nosepads and cable temples. The spectacles were given to 12 patients for use during postoperative face-down positioning. A questionnaire was used to evaluate the helpfulness of the spectacles during face-down positioning. RESULTS: Patients ranked the spectacles as "helpful" to "very helpful" with a mean and SD of 8.3+/-1.6 on a scale of 1 to 10, where 1 was "a hindrance" and 10 was "very helpful." Patients wore the spectacles an average of 5.7+/-4.5 hours a day (range, 1.5 to 15 hours). CONCLUSION: Modified bed spectacles appear to be a portable aid to patients who undergo face-down positioning while sitting, standing, or prone.

Gases↗

First-grade classroom behavior: its short- and long-term consequences for school performance.

Effects of children's classroom behavior on school performance over a 4-year period are examined for a large, representative panel of beginning first graders. Scales developed from homeroom teachers' ratings of children in the spring of their first, second, and fourth years of school are used to predict spring marks in reading and math and spring scores on verbal and quantitative subtests from the CAT battery. The teachers' ratings cluster in three domains: Interest-Participation (I-P), Cooperation-Compliance (C-C), and Attention Span-Restlessness (A-R). The I-P and A-R ratings, but not C-C ratings, affect test score gains in first grade and marks in all 3 years. Behavior ratings from Year 1 also affect Year 2 and Year 4 performance, with indications that effects are understated over single-year periods. The importance of assessing classroom behavior in a longitudinal framework that allows for lagged and cumulative effects is discussed.

Achievement↗

Detection of antibody responses and delayed dermal hypersensitivity with Blastomyces dermatitidis yeast and mycelial lysate antigens.

Yeast cell lysate and mycelial lysate antigens prepared from one strain (T-58) of Blastomyces dermatitidis were evaluated with respect to the detection of antibodies and delayed dermal hypersensitivity. Comparable ELISA sensitivity values were evidenced with the two antigens when assayed against serum specimens from dogs with blastomycosis, sera from non-infected dogs residing in endemic and non-endemic areas for blastomycosis and sera from rabbits that were hyperimmunized with B. dermatitidis antigens. Specificity determinations with anti-Histoplasma capsulatum rabbit sera indicated that both reagents exhibited only minimal cross-reactivity; the mycelial antigen was slightly more specific than the yeast phase reagent. Similar sensitivity and specificity results were experienced when the two antigens were used to detect delayed dermal hypersensitivity in guinea pigs previously sensitized with B. dermatitidis or H. capsulatum.

Animals↗

Beginning school math competence: minority and majority comparisons.

This article uses a structural model with a large random sample of urban children to explain children's competence in math concepts and computation at the time they begin first grade. These 2 aspects of math ability respond differently to environmental resources, with math concepts (reasoning) much more responsive to family factors before formal schooling begins than is computation. In this sample, blacks and whites are equivalent in terms of computational and verbal skills as measured by the California Achievement Test at the start of grade 1. However, there is a significant difference of about a quarter of a standard deviation favoring whites over blacks in terms of math concepts (reasoning skills). Both black and white children of all socioeconomic levels respond to parents' psychological resources: net of ability or other factors, children score higher if parents expect them to do well. Socioeconomic resources in the home also help both groups. In particular, the parent being a high school graduate as opposed to a dropout is important. When parents' material and psychological resources are taken into account, family configuration (solo motherhood vs. other types) has no discernible effects on either type of math performance.

Achievement↗

Achievement in the first 2 years of school: patterns and processes.

How successfully children adapt to the routine of schooling in the first grade or two likely has long-term implications for their cognitive and affective development. This study aims to understand how home and school factors either facilitate or impede this process of adaptation by examining longitudinal data on cognitive performance for a large and diverse sample of youngsters over grades 1 and 2 in Baltimore City Public Schools. Report-card marks in reading and mathematics and scores on verbal and quantitative subtests of the California Achievement Test (CAT) battery over the 2-year period are the achievement criteria. The analysis directs attention to some of the social-structural (socioeconomic background, gender, and minority/majority status) and social-psychological (significant others and self-reactions) factors that shape youngsters' development during this period, as measured by changes in their cognitive standing. Racial comparisons (black youngsters vs. white) and comparisons by school year (first vs. second) highlight some key differences in the transition to full-time schooling. We find more numerous social-structural and social-psychological influences on CAT gains over the first year than over the second, and fall to spring stability in testing levels is more pronounced in the second year than in the first. This pattern identifies the first year of schooling as a period of considerable consequence for shaping subsequent achievement trajectories, and, for this reason, it may be especially important as a key to understanding black-white achievement differences. Minority and majority youngsters in this sample began school with similar CAT averages, but, by the end of the first year, blacks' performances lagged noticeably behind those of whites, and the cleavage widened over the second year. Blacks also received lower report-card marks than whites. This, along with smaller CAT gains, reveals that the transition to school is more problematic for blacks than it is for whites. We also observed stronger persistence of blacks' marks from one period to the next, indicating that recovering from these initial difficulties is more challenging. Social-psychological aspects of these early achievement patterns also differ by race in important ways: blacks' achievements are less influenced by parent variables than are those of whites, and black youngsters' self-expectations are less affected by the expectations held for them by their parents than are those of whites. These results and others are discussed in terms of their implications for students' development and for what they reveal about social structure in relation to the early schooling process.

Achievement↗

The emergent academic self-image of first graders: its response to social structure.

One aim of this investigation was to determine the kinds of information a large and racially diverse sample of urban first-grade children take into account in forging their image of an academic self, especially the extent to which evaluations of significant others versus self-evaluations are influential. Another aim was to determine whether the nascent academic self-image affects the school achievement of these first-grade children. There was no difference in children's academic self-image according to race or parent background, but children of the 2 sexes defined their images differently. Girls' images strongly reflected stereotypic sex-role notions; boys' images reflected instrumental role concerns. Math performance was relevant only for boys. Boys depended more on self-evaluations than girls did, while girls depended more on parents' evaluations. Black girls were the only group for whom the academic self-image was a significant influence on achievement gains over first grade. The discussion points up the correspondence between these findings and what has been found for adolescents.

Achievement↗

Ketamine and the guinea-pig ileum: possible opiate agonist and antagonist actions and effects of peptidase inhibition.

The effects of ketamine and its interaction with naloxone were studied on the transmurally stimulated guinea-pig ileum preparation. Ketamine (at concentrations between 10(-4) and 10(-3) M) depressed the contractions of the ileum, showing a very steep log concentration-effect curve. Naloxone partially reversed the depressant effect of ketamine at slightly higher concentrations (between 10 nM and 1 microM) than those normally required to reverse opiate depression in this tissue. Naloxone did not affect pentobarbitone-induced depression, suggesting that ketamine has specific actions on opiate transmission. Phentolamine and propranolol did not affect the ketamine-induced depression, whereas acetylcholinesterase inhibition did not alter the action of naloxone on this depression. Ketamine showed some reversal effect on the depressant action of morphine and caused contractions of the morphine-tolerant ileum, suggesting that it may have opiate antagonist activity. Inhibition of peptidase enzymes by a mixture of dipeptides potentiated the depression after high-frequency stimulation of the ileum, but did not affect the action of ketamine. The results suggest that ketamine may interact with opiate mechanisms in the ileum to produce part of its depressant action and may also have some opiate antagonist activity.

Acetylcholine↗

Measurements of intraocular pressure made with multiple noncontact tonometers.

Intraocular pressure measurements were made on 30 normal eyes using seven noncontact tonometers. The instruments were from 4 to 8 years old. Results show that pressures indicated by most noncontact tonometers are not significantly different. In the most extreme case, differences in mean pressures of 3.48 mm Hg were obtained. A difference of this magnitude may be important when following a patient over a period of time, and could be the result of measurements being made on a different tonometer.

Humans↗

148 degrees fundus photography.

Clinical use of an innovative fundus camera system which takes extra wide-angle pictures is described. Advantages and limitations of the system are reviewed. Photographic patient examples are demonstrated.

Fluorescein Angiography↗

Some inflammations of the external eye and adnexa.

A selected review of "red eye" problems associated with the anterior segment is presented. Special attention is given to delineating similar diseases of the same tissue as ocular signs of the lid and sclera related to systemic disease are discussed.

Blepharitis↗

Glaucomatous cupping--appearance, pathogenesis, detection.

Increased optic disc cupping has long been associated with glaucoma. In this paper the appearance, pathogenesis, and detection of glaucomatous cupping is reviewed. Emphasis is given to the increase in cup-disc ratio and appearance of the peripapillary area as being diagnostic of glaucomatous atrophy. The vascular theory for producing these changes is outlined and represents the most comprehensive attempt at explaining the changes of the disc in glaucoma.

Glaucoma↗

Four clinical techniques in cup/disc ratio estimation.

Four clinical techniques for estimating cup/disc ratio were compared. Small differences in magnitude of the cup/disc ratio were found with each technique studied. In addition, a mean cup/disc ratio of between 0.22 and 0.30 was found for the subjects studied. The clinical utility of four funduscopic examination methods is reviewed.

Glaucoma↗