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Biomedical subjects

D R Anderson

Publications and source records attributed to D R Anderson.

At least 235 records · Page 13Linked to original sources

Young children's comprehension of montage.

2 studies examined children's comprehension of brief stop-animation televised segments incorporating elements of cinematic montage such as pans, zooms, and cuts. Children reconstructed the action and dialogue in these segments using the same dolls and settings depicted. In Study 1, there was no effect of cinematic techniques on reconstruction performance of 3- and 5-year-olds as compared to control segments filmed without these techniques. The results challenged the assumption that the use of such techniques per se contributes to young children's poor comprehension of television shows. In Study 2, 12 new segments were produced in which comprehending the montage required inferences of character perspective, implied action sequences, spatial relationships, and simultaneity of different actions. Averaging across all segments, 62% of the 4-year-olds and 88% of the 7-year-olds demonstrated clear comprehension of the montage. Inferences concerning implied action sequences were easiest for both ages. Inferences of simultaneity were most difficult for 4-year-olds, whereas inferences of character perspective were most difficult for 7-year-olds. Preschool children are thus capable of understanding cinematic events conveyed through camera techniques and film editing, despite previous assertions to the contrary. This ability nevertheless substantially increases with age.

Child↗

Early foveal involvement and generalized depression of the visual field in glaucoma.

We selected for study 35 patients with glaucomatous visual field loss or cupping that was asymmetric between the two eyes, concentrating on cases in which the glaucomatous damage was mild. We found that 15 patients had a reduced foveal sensitivity usually associated with either a scotoma impinging on fixation or a depression in the central field. In addition, 19 of the 35 patients had a subtle reduction in visual acuity. Thus, the fovea is often mildly affected early in glaucoma, even though the point of fixation is typically among the last regions of visual field to have a severe loss of visual sensation. We also observed that there is often a diffuse visual field loss early in glaucoma, represented as a generalized depression, and this may occur before there are discrete nerve fiber-bundle defects (paracentral scotomas and the like).

Fixation, Ocular↗

Static and kinetic visual field testing. Reproducibility in normal volunteers.

The SD of static visual threshold ranges from 0.12 log units near fixation to 0.41 log units 30 degrees from fixation. Among 60 points tested, most persons have at least one point that tests 0.5 log units less sensitive than the adjacent points, simulating a scotoma 0.5 log units deep. With automated kinetic perimetry, the SD of isopter position is 2.6 degrees to 5.5 degrees, with the greatest variation appearing in the temporal field where the slope is flatter and the isopters are more peripheral. More than 10% of the points show an inward deviation of 5 degrees or more compared with their neighboring points. Retesting of the deviant points is required to distinguish an artifact caused by variable responsiveness from true localized defects. Judgments about progression also require that the accuracy of the isopter position or threshold determination be taken into account.

Adult↗

Trabeculectomy in aphakic eyes.

One hundred twenty-seven trabeculectomies performed on aphakic eyes at the Bascom Palmer Eye Institute (BPEI) between 1972 and 1982 were reviewed. Forty-five cases were excluded from data analysis: 28 in eyes with confounding conditions, such as neovascular glaucoma; ten with follow-up of less than six months; and seven that were the second or third trabeculectomy performed at the BPEI in six eyes. Of the remaining 82 trabeculectomies in 82 eyes: 32 (39%) were categorized as successes (eyes that achieved an intraocular pressure of less than or equal to 21 mmHg with medication or less than or equal to 25 mmHg without medication); eight (10%) were categorized as qualified failures (eyes that had an intraocular pressure of greater than 21 mmHg despite medication or greater than 25 mmHg without medication); and 42 (51%) were categorized as complete failures (eyes that underwent further glaucoma surgery, had further glaucoma surgery recommended, or lost light perception). In the 20 eyes of the patients younger than 50 years of age, only one (5%) was categorized as a success; while in the 62 eyes of the patients 50 years of age or older, 31 (50%) were categorized as successes.

Adolescent↗

5-fluorouracil and glaucoma filtering surgery. II. A pilot study.

5-Fluorouracil (5-FU) was injected subconjunctivally after glaucoma filtering surgery in a pilot study of eyes with poor surgical prognoses. Twenty-seven (79%) of the 34 aphakic eyes with glaucoma achieved an intraocular pressure (IOP) of less than or equal to 21 mmHg (range of follow-up on nonreoperated eyes, 91 -468 days). Nine (69%) of 13 eyes with neovascular glaucoma achieved an IOP of less than or equal to 21 mmHg (range of follow-up on nonreoperated eyes, 120-379 days). Eight (89%) of nine phakic eyes with glaucoma following unsuccessful filtering procedures achieved an IOP of less than or equal to 21 mmHg (range of follow-up on nonreoperated eyes, 134-394 days). Visual acuities remained within one line of their preoperative levels or improved in 32 (94%) of the 34 aphakic eyes with glaucoma, eight (62%) of the 13 eyes with neovascular glaucoma, and six (67%) of the nine phakic eyes with glaucoma following unsuccessful filtering procedures. Postoperative corneal epithelial defects occurred in 45% of the cases. Conjunctival wound and conjunctival needle tract leaks were observed in 41% of the cases, but only one eye required wound revision. No other serious side effects that we attributed to 5-FU were observed. It seems that postoperative subconjunctival 5-FU increases the likelihood of achieving IOP control following filtering surgery in eyes with poor surgical prognoses; however, a randomized clinical trial is necessary to confirm this.

Adolescent↗

Toxicity of anticholinesterases: interactions of pyridostigmine and physostigmine with soman.

This investigation was conducted to assess the potential of carbamate pretreatment to exacerbate the ill effects of low doses of soman. Ambulatory Activity in a photocell cage (AA) and performance time on an accelerating rotarod (ARR) were used to test for interactions between pyridostigmine or physostigmine and soman. ED50s (i.e., dosages sufficient to reduce ARR time and AA to 50% of control level) of each carbamate (IM) and soman (SC) were determined. The ED50 values (mg/kg) in the ARR test were 3.2, 0.21, and 0.072 for pyridostigmine, physostigmine and soman, respectively, while in the AA test the corresponding values were 1.8, 0.072 and 0.060. The matrix of 16 combinations of 0, 1, 2/3, and 1/3 ED50 each of carbamate and soman was studied in each test system, as well as the effect of behavioral deficit free (BDF) dosages of each carbamate on the ED50s of soman. In both the AA and ARR tests the matrix of combinations of pyridostigmine and soman indicated an additive effect. In contrast, physostigmine produced one instance of potentiation in each test system and anatagonism in two combinations in the AA procedure. A BDF dosage of each carbamate (0.056 mg/kg of pyridostigmine and 0.026 mg/kg of physostigmine) gave no evidence of adding to the deficit in AA induced by soman. In the ARR test, the ED50 of soman was lower by 11% with pyridostigmine pretreatment and by 14% with physostigmine; the latter just reached statistical significance (p less than 0.05). Although additivity was most often found at higher dosages of pyridostigmine and physostigmine, at the BDF dosages little or no adverse interaction was found between Pyridostigmine or Physostigmine and low levels of soman.

Acetylcholinesterase↗

Treatment of selected patients with an ununited fracture of the proximal part of the scaphoid by excision of the fragment and insertion of a carved silicone-rubber spacer.

An ununited scaphoid fracture whose proximal fragment is small, sclerotic, fragmented, or badly deformed is usually not suitable for bone-grafting. We treated twenty-one such patients by excision of the small proximal fragment through a volar incision and the insertion of a hand-carved silicone-rubber spacer. After surgery, twenty patients (95 per cent) were able to return to work and engage in strenuous activities, including sports. Pain was significantly relieved, although wrist motions and grip were only minimally improved. Preoperative and postoperative comparative measurements of carpal collapse and translation showed only insignificant changes after this procedure.

Adult↗

Incomplete glycosylation of Asn 563 in mouse immunoglobulin M.

Mouse immunoglobulin IgM was prepared from MOPC 104E ascites fluid and [3H]-mannose labeled tumor cells. The purified protein was used to prepare Fc fragments which were cleaved by cyanogen bromide. Gel filtration allows complete separation of the C-terminal glycosylation site. Amino acid and carbohydrate analyses show that Asn 563 of murine IgM is glycosylated only about 44% of the time.

Amino Acids↗

Blockage of axonal transport in optic nerve induced by elevation of intraocular pressure. Effect of arterial hypertension induced by angiotensin I.

Previous studies have shown that elevation of intraocular pressure blocks rapid axonal transport at the lamina cribrosa of the optic nerve. In this study, IOP-induced blockage of axonal transport was greater in cats with elevation of BP induced by angiotensin I than in control animals with normal BP. The fact that cardiovascular factors influenced IOP-induced blockage of axonal transport suggests that it is due to ischemia; if the blockage were a direct mechanical effect of the IOP on the axons, it should be unaffected by BP. The data also suggest that the vasoconstrictive properties of angiotensin I reduced the ability of the vasculature of the optic nerve head to autoregulate when challenged by elevation of IOP.

Angiotensin I↗

Effect of elevated intraocular pressure on blood flow. Occurrence in cat optic nerve head studied with iodoantipyrine I 125.

Iodoantipyrine was used to record relative blood flow in the retina, choroid, optic nerve head, lamina cribrosa, and postlaminar optic nerve of cats at different levels of intraocular pressure. The IOP could be elevated to within 25 mm Hg of mean femoral arterial pressure, with only a slight effect on blood flow in the retina, choroid, and optic nerve head. At higher IOPs, the blood flow is reduced in the retina, choroid, and optic nerve head, but, in the lamina cribrosa, the blood flow is reduced only with extreme pressure elevation and is not reduced at all in the intraorbital optic nerve. Thus, there is no demonstrated effect of IOP on blood flow preferentially in the normal optic nerve. It is concluded that there is an efficient autoregulation in the optic nerve head and lamina cribrosa so that the IOP over a wide range does not much influence blood flow under normal circumstances. These findings do not rule out a role of ischemia in the pathophysiology of glaucomatous cupping, which may be caused by faulty autoregulation.

Animals↗

Dethecting glaucomatous damage with the Friedmann analyzer compared with te Goldmann perimeter and evaluation of stereoscopic photographs of the optic disk.

We used a Friedmann visual field analyzer with a 98-hole plate to test 32 normal control eyes and to establish highly specific criteria for abnormality. When these criteria were later applied to the testing of 50 additional normal control eyes, there were no false-positive abnormalities. With these criteria, the Friedmann visual field analyzer proved to be at least as sensitive as careful manual perimetry with the Goldmann perimeter in detecting early glaucomatous visual field defects. In addition to having high sensitivity and specificity, the Friedmann visual field analyzer with the 98-hole plate is rapid and requires very little training to operate. By way of comparison, examination of stereoscopic photographs of the optic disk was also sensitive in detecting or suggesting glaucomatous damage with visual field loss, but some of the normal control optic nerves were also considered suspect. Ignoring the suspect disks in order to reduce false-positive results improved specificity but simultaneously reduced sensitivity for detecting definite visual field loss. The combination of optic disk evaluation and visual field testing (with wither the Goldmann or the Friedman instrument) better detected early cases than did either test alone, because each method picked up some early cases missed by the other.

Adult↗

Quantitation of glaucomatous visual field defects with the Mark II Friedmann analyzer.

To evaluate the ability of the Friedmann visual field analyzer to determine visual threshold and the depth of visual field defects, we correlated the visual threshold determined kinetically (Goldmann perimeter) with the static threshold (Friedmann analyzer) in various parts of the central field. We found the following: the Friedmann working threshold correlated linearly with the height of the hill of vision represented by the position of the kinetic isopters of the Goldmann perimeter; the static visual threshold (Friedmann) at a particular location, whether normal or abnormal, was linearly related to the kinetic visual threshold (Goldmann) at that location; and the depth of all visual field defects was essentially the same with both instruments. Thus, the Friedmann analyzer accurately quantitated the central visual field in both the normal and abnormal regions, and may be advantageous for following the progress of early glaucomatous defects. For other patients, however, its usefulness may be limited, because defects outside 25 degrees cannot be documented, the visual field examination may be lengthy and inefficient when quantitating large defects of irregular depth, and the maximal quantitation of depth with the Friedmann analyzer is 2.0 log units less than with the Goldmann perimeter near fixation (but there is progressively less difference for defects further from fixation).

Aged↗

Trabeculotomy compared to goniotomy for glaucoma in children.

Trabeculotomy ab externo and goniotomy seem to be in many ways equivalent, and both are particularly successful in previously unoperated cases of primary infantile glaucoma that become apparent postnatally but before the age of 1 year. It may be more difficult to achieve a technically perfect procedure with trabeculotomy than it is with goniotomy, but trabeculotomy has an advantage in cases where the cornea is so cloudy that the angle cannot be seen well enough for goniotomy under direct visualization. Overall, the two procedures seem equally effective and safe.

Glaucoma↗

What happens to the optic disc and retina in glaucoma?

In glaucoma there is a spectrum of disc damage ranging from highly localized tissue loss (a notch in the neuroretinal rim), vertically oval cupping, or simple concentric enlargement of the cup. The accompanying visual loss may likewise range from a well-localized nerve fiber bundle detect to a generalized depression. Cases with diffuse loss of axons, a concentric enlargement of the cup, and a generalized reduction in visual function are more difficult to recognize unless the previous state of the disc and vision is well documented or there is asymmetry between the two eyes.

Axons↗

Eye tracking abnormalities in patients with cerebrovascular disease.

Ten patients with disequilibrium, ataxia, and cerebrovascular abnormalities were studied using computer aided eye tracking and vestibular function tests. The patients had severe abnormalities in smooth pursuit (decreased gain) and saccade tests (increased delay, decreased accuracy). Optokinetic responses were less affected. The gain of the vestibulo-oculomotor reflex was sometimes affected. Patients with eye tracking abnormalities frequently had symptoms of difficulty reading and watching television. When the lesion was asymmetrical, abnormal eye tracking tests usually pointed to the side of the lesion. Computer aided eye tracking tests are a useful adjunct to the evaluation of the patient with suspected vascular disease. They help to locate areas of central nervous system dysfunction, and produce an objective measurement of the severity of impairment. Conversely, when impairment of the smooth pursuit or saccade system is detected in patients being evaluated for disequilibrium, an assessment of the patients' cerebrovascular system should be considered.

Adult↗

Surgical therapy of traumatic hyphema.

The usual management of traumatic hyphemas in our institution has been to avoid or delay surgery until absolutely demanded by the clinical course. Despite this, most (73%) of our in-patients with total hyphema underwent surgery before leaving the hospital. In those who required surgery, 43% developed corneal staining. Optic nerve damage occurred in half of the patients whose surgery was performed eight or more days after the hyphema occurred, but was absent in those undergoing earlier surgery. The usual procedure used in this series was a trabeculectomy with iridectomy and gentle irrigation of the anterior chamber, and no surgical complications occurred. We believe that surgery, being relatively safe, should be performed early in cases of total hyphema unless the elevated intraocular pressure is controlled medically and spontaneous resolution is clearly imminent. For cases in which surgery is nearly inevitable, we suggest that earlier surgery might reduce the incidence of optic nerve damage and corneal staining.

Adolescent↗