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Biomedical subjects

J A Fox

Publications and source records attributed to J A Fox.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

An improved method for illuminating pipet tips for fire-polishing.

Shining light down the long axis of a pipet causes the pipet tip and walls to glow, yet leaves the background dark. The resulting contrast, and the appearance of colored bands near the pipet tip, improves visualization of the tip, affording more precise control of fire-polishing. Existing fire-polishing apparatus can be easily modified to incorporate this type of illumination.

Fiber Optic Technology↗
PubMedDate not supplied

Neuropeptide-hydrolysing activities in synaptosomal fractions from dog ileum myenteric, deep muscular and submucous plexi. Their participation in neurotensin inactivation.

The mapping of neuropeptidases in synaptosomal fractions prepared from dog ileum myenteric, deep muscular and submucous plexus was established by means of fluorigenic substrates and specific inhibitors. Endopeptidase 24.11, angiotensin-converting enzyme and aminopeptidases were found in all tissues, the highest amounts being recovered in the submucous preparation. Post-proline dipeptidyl aminopeptidase was obtained in high quantities whatever the tissue source while proline endopeptidase was detected in low amounts and pyroglutamyl-peptide hydrolase was never detectable. The above peptidases were examined for their putative participation in the inactivation of neurotensin by monitoring the effect of specific inhibitors on the formation of the metabolites of labeled neurotensin separated by HPLC. Endopeptidases 24.11, 24.15 and 24.16 were respectively responsible for the formation of neurotensin(1-11), neurotensin(1-8) and neurotensin(1-10) that are devoid of biological activity. The secondary attacks occurring on neurotensin degradation products were the following: cleavage of neurotensin(1-10) into neurotensin(1-8) by angiotensin-converting enzyme; conversion of neurotensin(9-13) into neurotensin(11-13) by post-proline dipeptidyl aminopeptidase; hydrolysis of neurotensin(11-13) into free tyrosine by aminopeptidase(s).

Aminopeptidases↗
PubMedDate not supplied

Differentiation of VEP intermodulation and second harmonic components by dichoptic, monocular, and binocular stimulation.

Modulation by two temporal frequencies differentiates visual processing at the fundamentals (1Fs), second harmonics (2Fs), and second-order intermodulation components (IMCs), the latter created neurally as the sum or difference of the two modulation frequencies. Steady-state VEPs were recorded while stereo-normal adults viewed luminance or grating stimuli modulated by up to three temporal frequencies under dichoptic, monocular, or ordinary (binocular) viewing conditions arranged using liquid crystal light shutters. In Experiment 1, modulation of luminance by a single temporal frequency produced strong 1F and 2F VEP components, but modulation of gratings produced only 2Fs. Modulation by two temporal frequencies resulted in IMCs, often in the absence of evoked activity in the EEG at the 1Fs. IMCs were generally larger during pattern as compared to luminance modulation. Amplitudes of 1Fs and IMCs were smaller, but 2Fs were larger, during dichoptic as compared to ordinary viewing. Although the 2F to a single modulation presented to one eye was not reduced when a second frequency was added to the opposite eye, monocular IMCs were diminished when a frequency was added to the opposite eye. We conclude that 2Fs and IMCs are associated with different neural substrates. Results are consistent with a two pathway model with one pathway having a nonlinear filter prior to binocular combination, the other pathway having a nonlinearity following binocular linear summation. Implications of these data for binocular function are discussed.

Adult↗
PubMedDate not supplied

Treatment of adolescent Blount disease with the circular external fixation device and distraction osteogenesis.

The purpose of this study was to review both the anatomic and functional results of treatment of adolescent tibia vara with distraction osteogenesis by using the circular external-fixation device. Twelve tibias in eight patients were treated. Preoperative proximal tibial varus averaged 18 degrees (range, 7-26 degrees). Postoperatively the mean deviation from standard anatomic alignment of the proximal tibia was 2.5 degrees (range, 0-7 degrees). All patients were allowed to weight bear as tolerated throughout the 12 weeks of frame wear. Function was assessed by knee score and was improved in all patients at a mean follow-up of 23 months. There were no neurovascular complications or delayed unions. One patient required return to the operating room because of premature consolidation of his regenerate.

Adolescent↗