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Biomedical subjects

B L Lam

Publications and source records attributed to B L Lam.

59 records · Page 4Linked to original sources
PubMed1989

Kestenbaum's number as an indicator of pupillomotor input asymmetry.

We compared the direct light response of both eyes in 90 patients who had anterior visual pathway disease using two different testing methods. We measured Kestenbaum's number in millimeters of pupillary diameter. Kestenbaum's number (K) is the difference in the pupil size attained in each eye under direct illumination while the other eye is occluded. We then measured the relative afferent pupillary defect (RAPD) in log units using neutral density filters. The two tests gave similar results (K = 0.88 x RAPD). Kestenbaum's number is the less precise measure, but it can be quickly and cheaply estimated even in dark brown eyes. The filter test requires a set of filters and at least one well-innervated iris sphincter. Kestenbaum's number can be measured without filters, but the iris sphincter and dilator muscles in both eyes must be normally innervated.

Filtration↗
PubMed1987

The prevalence of simple anisocoria.

We photographed the pupils of 128 normal subjects in dim light, morning and afternoon, for five consecutive days. Fifty-two of the subjects (41%) had an anisocoria of 0.4 mm or more at one time or another during these five days, but only four (3%) had unequal pupils of 0.4 mm or more in all ten photography sessions. At any given examination, a fairly constant 19% (24 of 128) of the subjects showed this amount of anisocoria. These numbers shifted dramatically when anisocoria was defined as a pupillary inequality of greater than, or less than, 0.4 mm. The prevalence of anisocoria did not vary with the time of day, from day to day, or from week to week, nor was it influenced by the sex, age, or iris color of the subject.

Adolescent↗
PubMed1980

Inhibitors of phenylethanolamine N-methyltransferase and epinephrine biosynthesis. 1. Chloro-substituted 1,2,3,4-tetrahydroisoquinolines.

In a search for inhibitors of epinephrine biosynthesis as potential therapeutic agents, a series of 13 ring-chlorinated 1,2,3,4-tetrahydroisoquinolines was prepared. These compounds were tested initially for their ability to inhibit rabbit adrenal phenylethanolamine N-methyltransferase (PNMT) in vitro. Enzyme-inhibitor dissociation constants, determined for the six most potent members of the series, indicated the following order of decreasing potency: 7,8-Cl2 greater than 6,7,8-Cl3 greater than 7-Cl approximately 5,6,7,8-Cl4 greater than 5,7,8-Cl3. These compounds were subsequently examined for PNMT-inhibiting activity in intact rats and mice. 7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline (13, SK&F 64139) was the most potent member of the series both in vitro and in vivo and is currently undergoing clinical investigation.

Adrenal Glands↗
PubMedDate not supplied

The c-wave of the electroretinogram recorded under clinical conditions from rabbits.

To determine whether large and repeatable c-waves can be recorded from rabbits with equipment already in use in clinical electroretinographic laboratories, the Burian-Allen electrode, connected bipolarly or monopolarly, was used to record electroretinograms from pigmented rabbits. The Jet electrode was also used. The c-waves elicited by long-duration (4-second) stimuli were compared to those elicited by stroboscopic stimuli. In addition, the c-waves recorded with direct-coupled amplification were compared to those recorded with condenser-coupled amplification (one-half-amplitude bandpass=0.1 Hz). The b-wave amplitude was not altered by the amplifier coupling or by the two stimulus durations. The largest c-waves were elicited by 4-second-duration stimuli and recorded with direct-coupled amplification. Although the c-wave amplitude was reduced by stroboscopic stimuli and by condenser coupling, large and repeatable c-waves were elicited by stroboscopic stimuli and recorded with condenser-coupled amplification. A comparison of stimulus duration and amplifier coupling showed that the stimulus duration was more important in recording large-amplitude c-waves. Similar results were obtained with the Jet electrode. We conclude that repeatable and large c-waves can be elicited by a stroboscopic stimuli and can be recorded with condenser-coupled amplification with good low-frequency response from rabbits.

Animals↗