Biomedical subjects

K A Manning

Publications and source records attributed to K A Manning.

6 recordsLinked to original sources

PubMed1991

Spermidine acetylation in response to a variety of stresses in Escherichia coli.

Heat shock, cold shock, ethanol, and alkaline shift, but not hydrogen peroxide, stimulate the accumulation of monoacetylspermidine in Escherichia coli. Acetylation occurs with nearly equal frequencies at both the N1 and N8 positions of this ubiquitous polycation. Spermidine acetylation does not appear to be associated with known stress regulons, such as htpR, oxyR, and SOS. E. coli, capable of acetylating spermidine, constitutively express a spermidine acetyltransferase activity during all phases of growth, and this activity is unaffected by cold shock. A mutant strain, incapable of acetylating spermidine, does not express this enzyme activity but grows at an identical rate as the parent strain at 37 degrees C. These results demonstrate that the monoacetylation of spermidine in E. coli is regulated by some mechanism other than a stress-inducible acetyltransferase and is not essential for growth of these cells. They suggest that polyamine acetylation is involved in the responses of these organisms to a variety of chemical and physical stresses.

Acetylation↗

PubMed1991

Eyelid movements in facial paralysis.

We studied the eyelid movements of six patients with unilateral, isolated, facial paralysis using the magnetic search coil. The most significant abnormality consisted of a reduction in the magnitude of the orbicularis oculi contraction with slowing of the peak velocity of the closing phase of the blink. The closing phase blink velocity, which normally increases linearly as a function of amplitude (main sequence), in our patients displayed a relationship characterized by a slow saturating power function that fell off the main sequence. The contralateral normal lid in some cases can show adaptive signs of hyperactivity during the closing phase of the blink. Lid saccades showed a small but consistent decrease in amplitude and velocity compared with the contralateral unaffected eyelid. Unlike the closing phase of the blink, peak velocities of lid saccades stayed on the main sequence. In this study, we discuss how the eyelid executes downward lid saccades based purely on a passive mechanism.

Adult↗

PubMed1991

Eyelid movements. Mechanisms and normal data.

This study provides a comprehensive description of upper eyelid movement in normal human subjects. Using the magnetic search coil technique to monitor lid position and modified skin electrodes to record orbicularis oculi electromyographic (EMG) activity, the authors found that the basic eyelid movements, blinks, and saccadic lid movements, can be uniquely and reliably characterized by their amplitude-maximum velocity relationships. The data show that similar increases in levator palpebrae activity produce the upward lid movements that accompany upward saccadic eye movements as well as the upward phase of a blink. The lid movements that accompany downward saccadic eye movements arise almost exclusively from the passive downward forces and relaxation of the levator palpebrae muscle. In contrast, active orbicularis oculi contraction and the passive downward forces act together to generate lid closure with a blink. These normative data and techniques provide the basis for the clinical analysis of lid motility by which abnormal lid movements can be compared with normal lid kinematics.

Adult↗

PubMed1990

Retrograde transneuronal transport properties of fragment C of tetanus toxin.

The atoxic fragment C of tetanus toxin reliably undergoes retrograde direct and transneuronal transport, but the full extent of its transport capabilities has not been examined. The primary visual pathways provide an excellent system for investigating, for the first time, the possibility of anterograde direct and transneuronal transport of fragment C. Following injection into the eye of the rat and rabbit, fragment C, localized with a monoclonal antibody, underwent anterograde direct transport to all retinorecipient areas. From these areas, fragment C exhibited retrograde transneuronal transport, strongly and reliably labeling regions that project to retinorecipient areas, including layers V and VI of visual cortex, the parabigeminal nucleus, the suprageniculate nucleus, and the reticular thalamus. In contrast, the absence of fragment C in regions receiving only input from, but not projecting to, retinorecipient areas, most notably layer IV of visual cortex, provides strong evidence for the lack of anterograde transneuronal transport. Thus, while fragment C can be induced to undergo anterograde direct transport by injection into the eye, it exhibits only retrograde transneuronal transport. These characteristics suggest that fragment C of tetanus toxin is a consistent and reliable retrograde transneuronal marker for the elucidation of central nervous pathways.

Animals↗

PubMed1979

Infant vision testing by a behavioral method.

A behavioral method of screening binocular infant vision called forced choice preferential looking (FPL) has been developed. Clinical trials of the FPL test for young infants are reported here. The test aids nonspecialized personnel in early identification of bilateral ocular abnormalities and anomalies of binocular cooperation (strabismus). It is not possible to screen for monocular eye disease or amblyopia with this test. Modifications of the FPL test may offer new ways of assessing other aspects of visual function early in life.

Age Factors↗

PubMed1978

A behavioral method for efficient screening of visual acuity in young infants. II. Clinical application.

Visual performance in 130 infants was assessed in a clinical setting with the forced-choice preferential looking (FPL) method described by Dobson et al.5 Over 90% of infants completed testing. Testing usually required less than 10 min. One group of infants tested also underwent complete ophthalmic examination. The second, larger group was screened with handlight examinations and FPL testing; any abnormalities detected were evaluated by full ophthalmic examination. Results so far indicate that the FPL test accurately identifies babies with binocular visual problems and that, when coupled with a handlight examination, it provides efficient screening for ocular problems in infants 0 through 16 weeks of age (postterm).

Age Factors↗