Vernier acuity in amblyopic and nonamblyopic children

We measured vernier acuity in normal and amblyopic children using a procedure that resembles a video game and is suitable for testing most children older than 4 years old. In this procedure, subjects align bars using two keys of a computer keypad. Following binocular practice trials, monocular vernier acuity was measured in 38 control children, 5 to 15 years old, and in 18 children with histories of amblyopia. Vernier acuity was defined as the standard deviation of adjusted position across a block of six trials. Vernier acuity improved as a function of age in the control subjects, indicating developmental improvement. Amblyopic subjects with strabismus (n = 5) and with both anisometropia and strabismus (n = 8) showed markedly impaired vernier acuity in their amblyopic eyes, with vernier acuitys four to five times larger than those of age-matched controls. However, the amblyopic subjects who were anisometropic (n = 5), without any history of strabismus, were not significantly different from control subjects in either eye. Testing with bars and gratings gave similar results. To our knowledge, this is the first study showing that vernier acuity deficits seen in adult amblyopes are also seen in child amblyopes.

Purification and initial characterization of the ATP:corrinoid adenosyltransferase encoded by the cobA gene of Salmonella typhimurium

The cobA gene of Salmonella typhimurium and its product were overexpressed to approximately 20% of the total cell protein. CobA was purified to 98% homogeneity; N-terminal sequence analysis (21 residues) of homogeneous protein confirmed the predicted amino acid sequence. ATP:corrinoid adenosyltransferase activity was demonstrated in vitro to be associated with CobA. This activity was optimal at pH 8 and 37 degrees C. A quantitative preference was determined for Mn(II) cations and ATP. The apparent Km of CobA for ATP was 2.8 microM, and that for cob(I)alamin was 5.2 microM. Vmax was measured at 0.43 nmol/min. Cobinamide served as the substrate for CobA to yield adenosylcobinamide. Activity was stable at 4 degrees C for several weeks but was lost rapidly at room temperature (50% overnight). Dithiothreitol was required to maintain the enzymatic activity of CobA.

SKILL card results in amblyopic children

Two experiments were undertaken to assess high contrast-high luminance (HCHL) and low contrast-low luminance (LCLL) visual acuity as measured with the Smith-Kettlewell Institute Low Luminance (SKILL) card, in childhood amblyopia. In experiment 1, HCHL and LCLL visual acuity was measured in 11 amblyopic children and in 12 normal children of similar age. The results revealed that HCHL visual acuity was similar in the normal eyes and in the amblyopes' dominant eyes, and was abnormal in 91% of the amblyopic eyes. LCLL visual acuity was significantly worse in normal eyes compared to the amblyopes' dominant eyes, and was abnormal in only 64% of the amblyopic eyes. In experiment 2, HCHL and LCLL visual acuity was measured in seven previously tested amblyopic children, after a 5-month interval, and in six additional amblyopic children. In the amblyopic children who were tested twice, significant test-retest reliability for HCHL and LCLL visual acuity was found and visual acuity varied by 3.6%. The results of experiment 2 corroborated the results of experiment 1 from the amblyopic children. It is concluded that visual acuity in the amblyopic eye tends to normalize under low contrast-low luminance conditions. In addition, the mechanism(s) underlying amblyopia appear also to influence the dominant eye, resulting in superior visual acuity under low contrast-low luminance conditions.

Anti-infection treatment of a transcutaneous device by a collagen-rifampicine composite

The polyurethane surface of a transcutaneous energy transmitter, which is implanted into a subcutaneous pouch for a total artificial heart, was coated with a Type I atelocollagen and rifampicine composite to prevent the infection that frequently occurs in the interfacial space between the tissue and the device. The specimen obtained after 7 weeks from a transcutaneous energy transmitter placed in a dorsal subcutaneous pouch of a dog revealed noninfected but well-attached dermal tissue without specific epithelial down-growth around the transcutaneous energy transmitter surface at the pouch-orifice area. The transcutaneous energy transmitter implanted in the pouch adhered well to the subcutaneous tissues. The collagen matrix seemed to have provided a favorable environment for the regenerating dermal tissue to obstruct the interfacial space. The coated collagen-antibiotic composite was degraded.

Effect of light filters on contrast sensitivity function in normal and retinal degeneration subjects

Contrast sensitivity functions were measured with five light filters and without a filter, in the presence of a glare source, in 12 retinal degeneration subjects and 9 normal subjects. The light filters included yellow-tinted, CPF 527, NoIR 111, 0.6 neutral density and sunglasses with a 95% UV filter. Retinal degeneration subjects showed a mild improvement in contrast sensitivity at the higher spatial frequencies and maintained mean log contrast sensitivity with light filters which reduced photopic light transmission up to 75%. Normal subjects exhibited a systematic decrease of contrast sensitivity at higher spatial frequencies with all light filters and overall mean log contrast sensitivity was significantly correlated (r = 0.86, P < 0.025) with photopic light transmission of the filters. It is concluded that, when in the presence of a glare source, the benefits of certain light filters to retinal degeneration subjects is related to the reduction of overall photopic luminance.