[Serum concentration as selection factor in tissue culture. Cytogenetic studies of the mouse fibroblast (strain L)].
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Biomedical subjects
J Froehlich
Publications and source records attributed to J Froehlich.
Improving the reliability of pattern electroretinogram recording.
The pattern electroretinogram (PERG) is a small electrical response of the retina to a reversing checkerboard pattern, usually less than 6 microV in amplitude. Unfortunately, the PERG can be obscured by artifacts such as blinks, eye movements, poor fixation, and amplifier saturation. Amplitude criterion artifact rejection systems found on commercial signal averagers eliminate large amplitude artifacts but are insensitive to small amplitude artifacts associated with amplifier saturation. Such saturation often occurs for several recording sweeps after large amplitude signals such as eye blinks are rejected. The presence of post-saturation artifacts complicates clinical PERG analysis. In this paper we describe procedures to remove these small amplitude artifacts from the PERG. These include computer selection of inputs for averaging and use of tracings with small input numbers to approximate PERG amplitudes. These procedures greatly reduce the variability of PERG amplitudes in the normal population, making PERG amplitude a more reliable clinical measure.
Adolescent↗
The pattern electroretinogram: N95 amplitudes in normal subjects and optic neuritis patients.
Recent work has suggested that the N95 peak of the transient pattern electroretinogram (PERG) may be a more sensitive indicator of the late stages of retinal function prior to optic nerve activation than the P50 peak. In this report, we show that a new measure of N95 amplitude, based on digital filtering methods to identify a non-linear baseline before measurement, greatly reduced the amplitude variation in a population of 50 normal subjects when compared with two other plausible measures. We then used that new measure to follow the time course of N95 amplitudes in 12 optic neuritis patients. It was found that maintenance of a normal N95 amplitude at 6 months after onset of optic neuritis was always associated with excellent clinical recovery as measured by visual fields, acuity, presence or absence of an afferent pupil and optic atrophy, and contrast sensitivity (CS). Loss of N95 amplitude to below laboratory limits of normal was associated with abnormalities in these indicators of visual function. This study supports the idea that the N95 peak represents retinal ganglion cell function.
Adolescent↗
Knee fusion with intramedullary rods for failed total knee arthroplasty.
Knee fusion was obtained after failed total knee arthroplasty with the aid of internal fixation by use of intramedullary rods. The method has been used in eight cases, including difficult situations characterized by morbid obesity, segmental fractures, and loss of bone stock. In these cases, stability would have been difficult to obtain with conventional methods of external fixation, compression, or casting. Stability was achieved quickly with an intramedullary rod in eight cases; fusion was obtained in seven.
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