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Biomedical subjects

A Augsburger

Publications and source records attributed to A Augsburger.

17 recordsLinked to original sources
PubMed1999

BMPs as mediators of roof plate repulsion of commissural neurons.

During spinal cord development, commissural (C) neurons, located near the dorsal midline, send axons ventrally and across the floor plate (FP). The trajectory of these axons toward the FP is guided in part by netrins. The mechanisms that guide the early phase of C axon extension, however, have not been resolved. We show that the roof plate (RP) expresses a diffusible activity that repels C axons and orients their growth within the dorsal spinal cord. Bone morphogenetic proteins (BMPs) appear to act as RP-derived chemorepellents that guide the early trajectory of the axons of C neurons in the developing spinal cord: BMP7 mimics the RP repellent activity for C axons in vitro, can act directly to collapse C growth cones, and appears to serve an essential function in RP repulsion of C axons.

Animals↗
PubMed1994

Floor plate and motor neuron induction by vhh-1, a vertebrate homolog of hedgehog expressed by the notochord.

The differentiation of distinct cell types in the ventral neural tube depends on local inductive signals from the notochord. We have isolated a vertebrate homolog of the Drosophila segment polarity gene hedgehog (hh) from zebrafish and rat, termed vhh-1. vhh-1 is expressed in the node, notochord, floor plate, and posterior limb bud mesenchyme. Each of these cell groups has floor plate inducing activity, suggesting that the vhh-1 gene may encode a floor plate-inducing molecule. Widespread expression of rat vhh-1 in frog embryos leads to ectopic floor plate differentiation in the neural tube. In vitro tests for the signaling functions of vhh-1 demonstrate that COS cells expressing the rat vhh-1 gene induce floor plate and motor neuron differentiation in neural plate explants. vhh-1 may, therefore, contribute to the floor plate and motor neuron inducing activities of the notochord.

Amino Acid Sequence↗
PubMed1982

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↗
PubMed1981

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↗
PubMed1980

A patient record review in a teaching clinic.

A description of a clinic patient record review process completed during a recent ten week period at our teaching clinic is presented. The review was done by peer groups of clinicians including both students and clinical faculty. Consistent improvement in the percentage of records judged appropriate occurred during the ten week period. Educational as well as quality control advantages of this process are cited.

Clinical Competence↗
PubMed1979

Reflectance of visual acuity screens.

The luminance of the background and of the target (visual acuity letter) was measured for five commonly used visual acuity screen materials. Most materials were found to be highly nonlambertian. A greater than threefold difference in reflectance normal to the surface was found for the respective screens tested. The percent polarization maintained by each screen material, using American Optical Vectograph systems, was measured. The relative illuminations generated by eight projector systems were compared. A discussion of the factors and recommendations for improvements related to projected chart visibility are made.

Field Dependence-Independence↗
PubMed1978

Evaluation of ophthalmic materials.

Ophthalmic materials from 11,677 spectacle-prescription orders were evaluated during an 18-mo period in a university optometry clinic. Five percent of the orders received were not acceptable based on criteria stemming from the ANSI-Z80. 1-1972 standards. Almost two-thirds of these rejections were lens related. Frame-related rejections were predominantly due to gross human error. Rejection rate and delivery time varied widely among the supplying laboratories. Rejection rate did not decrease with increased delivery time. Since notifying the laboratories of our results, the percentage of unacceptable orders has decreased.

Evaluation Studies as Topic↗
PubMed1977

Non-contact and Mackay-Marg tonometry: comparison in patients ages 7 to 85 years.

In a sample of 212 eyes of patients referred to an ocular pathology clinic, measures of intraocular pressure (IOP) using the non-contact tonometer (NCT) and the Mackay-Marg tonometer were highly correlated (+0.91), the NCT MEASURES BEING LOWER BY AN AVERAGE OF 6.5 MM Hg. In a general optometry clinic, the mean IOP as measured with the NCT on 987 eyes of patients, ages 7 to 85 years, was 15.7 mm Hg (S.D.=3.5 mm Hg). Stability of IOP was age, found for this sample, is unexpected if IOP is proportional to systemic blood pressure which rises with age. Several hypotheses propose to explain the apparent inconsistency.

Adolescent↗
PubMed1977

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↗
PubMed1976

Effects of non-contact tonometry on refraction.

The spherical component of refractive error was measured subjectively before and after noncontact tonometry in 19 eyes and also on the fellow (control) eyes without tonometry. No significant change in this measure of refractive error was found after tonometry. The tested group could not be distinguished from the control group.

Adult↗
PubMed1975

Clinical tonometric measurements comparing three non-contact tonometers.

Three American Optical Non-contact Tonometers were used to compare readings against each other. The attempt was to determine if all three tonometers were measuring the same IOP over a wide range of pressures. The assumption in practice is that all Non-contact Tonometers are manufactured within tolerance that should allow the examiner to find that same IOP on a patient regardless of the Non-contact Tonometer used. A preliminary study found no significant difference between the instruments.

Adolescent↗