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Biomedical subjects

B Luna

Publications and source records attributed to B Luna.

33 records · Page 2Linked to original sources
PubMed1996

Interobserver reliability of the Teller Acuity Card procedure in pediatric patients.

PURPOSE: To compare interobserver agreement for Teller Acuity Card estimates of grating acuity between children with ocular or neurologic abnormalities, or both, and age-matched healthy preterm children. METHODS: Subjects were 57 children, 3 to 38 months of age, who were referred for visual assessment because of diagnosed or suspected visual impairment (clinical group), and 57 healthy preterm children with no known visual or neurologic abnormalities (control group), each of whom was matched to a clinical subject, based on corrected age at the time of testing, and type of testing (monocular or binocular). Each child's grating acuity was tested by two independent observers. RESULTS: Interobserver agreement of 1 octave or better was found in 91% of the monocular and 96% of the binocular clinical test-retest comparisons and in 95% of the monocular and 96% of the binocular control comparisons. For estimates of interocular acuity difference, interobserver agreement of 1 octave or better was found in 88% of clinical subjects and 88% of control subjects. Average test time was significantly longer in the clinical group (4.1 minutes [SD = 1.9] for monocular and 3.6 minutes [SD = 1.9] for binocular tests) than in the control group (2.5 minutes [SD = 0.9] for monocular and 2.4 minutes [SD = 0.6] for binocular tests), suggesting that children in the clinical group were more difficult to test. CONCLUSIONS: Teller Acuity Card testing conducted by experienced testers is as reliable in children with mild to severe ocular or neurologic abnormalities as it is in healthy children, even though children with abnormalities may be more difficult to test.

Child, Preschool↗
PubMed1996

Locomotion while load-carrying in reduced gravities.

Supporting the mass of a protective suit and portable life support system (PLSS) will impose an energy requirement on planetary astronauts. To design extravehicular protective equipment for planetary missions, scientists must learn more about human physical capabilities while load-carrying in reduced gravities. In this study, an underwater treadmill and weighting system were used to simulate reduced-gravity locomotion while load-carrying. The test matrix included 3 gravity levels, 6 subjects, 2 locomotion speeds, and a range of load sizes. Energy expenditure, calculated from measured oxygen consumption, is positively correlated with gravity level, speed, and load size. The data are used to project that individuals in average physical condition will be able to walk for 8 h on the Moon while carrying up to 170% of their body mass without undue fatigue, and on Mars with up to 50% of their body mass. These approximate limits, especially for Martian gravity, may prove quite a challenge for designers of advanced protective systems. Requirements for regenerable and non-venting PLSS components have been driving the total projected masses of advanced PLSSs increasingly higher, perhaps beyond what is reasonable to carry. However, the larger mass can be beneficial in maintaining bone mass. Using Whalen's model (1988), the daily planetary walking times required to maintain bone mass were calculated for a range of carried load sizes. The calculated times were unattainably high, suggesting that some combination of loads carrying and supplemental bone maintenance measures will likely be required to maintain bone mass in reduced gravity environments.

Bone Density↗
PubMed1995

Grating acuity and visual field development in infants following perinatal asphyxia.

Grating acuity and visual fields were assessed in 66 children who had had perinatal asphyxia (ASPH). Also tested were 41 healthy preterm children (H-PT). Subjects were tested at birth to one month, and four, nine, 12, 17, 24, 30 and 36 months corrected age. The mean acuity scores of the ASPH group were lower than those of the H-PT group at most test ages, and significantly so at 30 and 36 months. The mean visual field size of the infants in the ASPH group was significantly smaller than that of the H-PT group at nine, 12, 30 and 36 months. No significant effects were found for preterm vs term birth, gestational age at birth, degree of asphyxia and presence of strabismus. However, central nervous system abnormalities (intraventricular haemorrhage and periventricular leukomalacia) were related to deficits in acuity and visual field size.

Asphyxia Neonatorum↗
PubMed1994

Development of grating acuity, letter acuity, and visual fields in small-for-gestational-age preterm infants.

Visual acuity and visual field development were assessed longitudinally in 21 preterm children who were born small-for-gestational-age (SGA) and in 51 preterm children who were appropriate-for-gestational-age (AGA). Grating acuity was tested binocularly at 0-1 month and monocularly at 4, 9, 12, 18, 24, 30, 36 and 48 months corrected age, using Teller acuity cards. Visual fields were measured binocularly using kinetic perimetry at the same ages. Recognition (letter) acuity testing was attempted using the crowded HOTV test in all subjects who came in for testing at 36 and 48 months. Children in the SGA group were matched to children in the AGA group by gestational age (+/- 3 weeks) and type of perinatal medical complications. There were no significant differences in grating acuity or binocular visual field size between the SGA and AGA groups. 78% of acuity scores for individual SGA-AGA pairs fell within one octave of perfect agreement. Binocular visual field size for each SGA-AGA pair also showed good agreement. Fewer SGA than AGA subjects were able to perform recognition acuity testing, and those SGA subjects who were able to perform the test, showed consistently poorer recognition acuity than their AGA counterparts. Thus, being SGA does not pose an additional risk for the development of grating acuity or binocular visual field size over the first 4 years of life in preterm children. SGA preterm children may be at risk, however, for acuity deficits when acuity is measured with the more complex targets and the greater test distance used to measure recognition acuity.

Child, Preschool↗
PubMed1993

Influence of jet impingement on color Doppler parameters of aortic regurgitation.

In vitro studies have demonstrated that the characteristics of a color Doppler jet are influenced by a number of factors including jet eccentricity and jet impingement. To explore the relationship of a jet impingement and aortic regurgitant color Doppler jet parameters, jet area, width, and length were measured from apical echocardiographic views of 84 patients 4 +/- 11 days prior to catheterization and compared to angiographic grade. An impinging color jet contacted the interventricular septum or mitral valve beneath the aortic valve in the imaging plane and a nonimpinging jet did not contact the septum or mitral valve in the imaging plane. As expected, the percentage of patients with impinging jets increased with aortic regurgitation angiographic grade. Neither left ventricular chamber dimensions nor the presence of an aortic prosthesis significantly influenced the color Doppler variables. For a given angiographic grade of aortic regurgitation, impinging jets were associated with larger color Doppler jet widths (P less than 0.05) and areas (P = 0.001) than nonimpinging jets. The color Doppler area and length increased significantly with angiographic grade for nonimpinging jets (P less than 0.05) but not for impinging jets. Impinging jets are associated with larger color Doppler widths and areas than nonimpinging jets for a given grade of aortic regurgitation, possibly because of the effect of jet deflection toward an adjacent wall. Jet impinging should be considered when using color Doppler techniques to evaluate aortic regurgitation.

Aged↗
PubMed1992

Grating acuity and visual field development of infants with bronchopulmonary dysplasia.

The grating acuity and visual fields were assessed of 48 infants with bronchopulmonary dysplasia (BPD) who had no periventricular leukomalacia or grade III or IV intraventricular hemorrhage, and no stage 3 or greater retinopathy of prematurity. Infants were tested at four, eight, 11, 17 and 24 months corrected age, and their results were compared with those of 81 healthy preterm infants and 54 with hyaline membrane disease (HMD) that did not result in BPD. The BPD group showed no significant difference in acuity development compared with the healthy preterm and HMD groups. Infants with BPD had significantly smaller visual fields than either control group at 11 months; visual field development was similar for all groups at all other test ages. The authors conclude that infants with BPD who have no significant ocular or neurological complications show normal grating acuity and visual field development during the first two years of life.

Bronchopulmonary Dysplasia↗
PubMed1990

Development of grating acuity in infants with regressed stage 3 retinopathy of prematurity.

The acuity card procedure was used to measure grating acuity in 17 infants with regressed Stage 3 retinopathy of prematurity (ROP) who had no lasting anatomic changes in the retina or optic nerve. Results were compared with those of 28 healthy preterm infants and 28 infants matched by birth weight and gestational age who did not have Stage 3 ROP. Infants in the ROP group showed delayed grating acuity development until 2 years of age. This difference among groups was significant at the 3-5- and 10-12-month test ages but not at the 0-1-, 8-9-, and 16-18-month test ages. Post hoc analyses indicated that the delay in acuity development shown by the ROP group was due to the poor acuity scores of the infants in that group who had central nervous system abnormalities of periventricular leukomalacia or severe (Grade III or IV) intraventricular hemorrhage. When the data of these infants were removed from the analysis, the ROP group showed acuity development similar to that of both the healthy preterm group and the group of infants with matched birth weights and gestational ages who did not have Stage 3 ROP.

Birth Weight↗
PubMed1989

Visual field development in infants with stage 3 retinopathy of prematurity.

Binocular visual field development was measured in 11 infants who had stage 3 ROP in early infancy and in 11 infants without ROP, matched for birthweight and gestational age. Kinetic perimetry was used to measure visual fields along the 45 degree, 135 degree, 225 degree and 315 degree half-meridia. Infants were tested at 4, 9, and 18 months from due date. Analyses of variance were used to compare results of the two groups for each age tested. Results at the 4-month test age indicated that both groups had visual fields within the normal range for their age. However, at the 9-month test age the ROP group showed a significantly (P less than 0.05) smaller visual field than the control group. At 18 months, the ROP group still showed smaller visual fields than the control group, but the difference was not significant. The results suggest that dysfunction of the peripheral retina associated with ROP may produce a constriction of the visual field or a delay in visual field development.

Aging↗
PubMedDate not supplied

Inhibitory control of attention declines more than working memory during normal aging.

Changes in frontostriatal systems are believed to reduce the efficiency of executive cognitive functions during normal aging, especially the inhibitory control of attentional and behavioral responses. To characterize changes during normal aging in sensorimotor, working memory and inhibitory attentional systems, we tested 20 healthy elderly subjects (age 65-80) and 28 young adults (age 18-34) using oculomotor paradigms. Visually guided saccades of elderly subjects showed decreased peak velocity and increased reaction time, but not reduced accuracy, indicating selective age-related declines in sensorimotor systems. In an oculomotor working memory task, memory for spatial location information in elderly subjects was as accurate as in young adults. In contrast, elderly subjects demonstrated a significantly reduced ability to voluntarily inhibit eye movements toward flashed targets on an antisaccade task. These findings indicate changes in frontostriatal systems during normal aging that adversely affect volitional inhibitory processes but spare encoding and retrieval components of spatial working memory.

Adolescent↗
PubMedDate not supplied

Dorsal cortical regions subserving visually guided saccades in humans: an fMRI study.

Neurophysiological studies in non-human primates have identified saccade-related neuronal activity in cortical regions including frontal (FEF), supplementary (SEF) and parietal eye fields. Lesion and neuroimaging studies suggest a generally homologous mapping of the oculomotor system in humans; however, a detailed mapping of the precise anatomical location of these functional regions has not yet been achieved. We investigated dorsal frontal and parietal cortex during a saccade task vs. central fixation in 10 adult subjects using functional magnetic resonance imaging (fMRI). The FEF were restricted to the precentral sulcus, and did not extend anteriorly into Brodmann area 8, which has traditionally been viewed as their location in humans. The SEF were located in cortex along the interhemispheric fissure and extended minimally onto the dorsal cortical surface. Parietal activation was seen in precuneus and along the intraparietal sulcus, extending into both superior and inferior parietal lobules. These findings localize areas in frontal and parietal cortex involved in saccade generation in humans, and indicate significant differences from the macaque monkey in both frontal and parietal cortex. These differences may have functional implications for the roles these areas play in visuomotor processes.

Adult↗
PubMedDate not supplied

Physiologic and functional responses of MS patients to body cooling.

OBJECTIVE: The objective of this study was to compare the responses of multiple sclerosis (MS) patients to short-term cooling therapy using three different vest configurations. DESIGN: Each garment was used to cool 13 male and 13 female MS subjects (31-67 yr). Oral and right and left ear temperatures were logged manually every 5 min. Arm, leg, chest, and rectal temperatures, heart rate, and respiration were recorded continuously on a Biolog ambulatory monitor. Each subject was given a series of subjective and objective evaluation tests before and after cooling. RESULTS: The Life Enhancement Technologies and Steele vests test groups had similar, significant (P < 0.01) cooling effects on oral and ear canal temperatures, which decreased approximately 0.4 degrees C and 0.3 degrees C, respectively. The Life Enhancement Technologies active liquid cooling vest produced the coldest (P < 0.01) skin temperature and provided the most improvement on subjective and objective performance measures. CONCLUSIONS: These results show that the various garment configurations tested do not produce similar thermal responses in all MS patients. The circulating liquid cooling vest was found to be more effective than either of the two passive cooling garments tested.

Activities of Daily Living↗
PubMedDate not supplied

Partial left ventriculectomy (Batista procedure) in the treatment of dilated cardiomyopathy: Makati Medical Center Philippine experience.

In the Philippines patients with end-stage heart disease refractory to conventional medical and surgical treatment do not have alternative choices. More than 99% of the population cannot afford cardiac transplantation. Partial left ventriculectomy (PLV) is a surgical procedure that improves cardiac function and refractory congestive heart failure (CHF). Between October 1997 and February 1998 eight patients had PLV at the Makati Medical Center, Philippines. All patients had end-stage dilated cardiomyopathy. Six patients had an idiopathic etiology, one was ischemic and one valvular. Seven of eight operations were done with the heart beating and all had transesophageal echo monitoring. An average of a 2-cm reduction in the left ventricle diameter was achieved and ejection fraction improved in all cases. There were no operative deaths. There were three late deaths. Two patients died of refractory CHF and ventricular arrhythmias and one patient died of massive cerebral hemorrhage with coumadin therapy. The five survivors are all doing well with no CHF. Follow-up two-dimensional echo shows stable left ventricular (LV) size and improved ejection fraction. Our initial experience shows that PLV, at least in the short-term, has beneficial effects in the treatment of end-stage dilated cardiomyopathy and might become an alternative to cardiac transplantation.

Adult↗