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Identical twins with congenital nystagmus were examined and studied with eye movement recordings and videotaping. The nystagmus differed in its location of the null zone, its frequency and amplitude, the degree of persistence in the dark, and the degree of impairment of pursuit and optokinetic nystagmus. As the two boys have the identical genetic constitution, we postulate that the discordant features of the nystagmus represent variable expressivity or, alternatively, the influence of environmental factors.

We have identified a family affected with X-linked recessive Norrie disease, in which a recombinational event occurred between the disease locus and the DXS7 locus identified by the probe L1.28. The addition of our family brings the total of published informative families to seven, with a maximum lod score of 7.58 at a recombination frequency of 0.038 +/- 0.036. This finding indicates that the L1.28 probe is useful but may not be completely reliable for prenatal diagnosis and that the gene for Norrie disease is not within the DNA sequence identified by the L1.28 probe.

In a retrospective study, a computer-based stepwise discriminant analysis was used to create a biostatistical model of the results of surgery in acquired esotropia. One hundred seventy-two patients who had bilateral medial rectus muscle recession as an initial operative procedure with at least 6 months postoperative follow-up were studied. The outcome groups for the discriminant analysis were based on the ocular deviation 6 weeks after the first surgery and at the patient's last visit, or the presence or absence of stereopsis at the last visit. With respect to the two predominant ocular deviation groups (Esotropia or Success) 6 weeks after surgery, 11 independent variables were analyzed; those determined to be prognostic of the outcome grouping were refractive error of the left eye and preoperative deviation, in that order. With respect to ocular deviation at last visit, 146 patients were followed for over 2 years and were last examined when over 5 years of age; of the 12 independent variables analyzed, postoperative deviation at 6 weeks, refractive error of the right eye, and age of onset were predictive. With respect to stereopsis, 126 patients had similar follow-up; of the 11 independent variables analyzed, only postoperative deviation at 6 weeks was prognostic. The results indicate that in patients with acquired esotropia the postoperative deviation is the most important prognostic factor for both the maintenance of ocular alignment and the status of stereopsis; refractive error and the age of onset of the esotropia influence the ocular alignment at the last visit.

Eye movements were recorded with electro-oculography in seven patients with rod monochromatism (RM) and five with blue-cone monochromatism (BCM). The continuous horizontal nystagmus was similar in both groups. However, three patients with BCM demonstrated an intermittent, high-frequency nystagmus, in addition to the continuous nystagmus. The most striking differences between the groups were present during monocular smooth pursuit and optokinetic tracking. Patients with RM demonstrated better tracking when targets moved in the temporal-to-nasal (T-N) direction in the visual field of the viewing eye, than when targets moved in the nasal-to-temporal (N-T) direction. The velocity of optokinetic nystagmus (OKN) increased gradually over several seconds during T-N target movement. Patients with BCM did not show a directional asymmetry or a slow build-up of OKN during monocular tracking. Differences in eye movement abnormalities can be useful in differentiating these two forms of congenital color blindness from other forms of congenital nystagmus and from each other.

Previous study has shown that the usual DNA marker for Norrie disease, the L1.28 probe which identifies the DXS7 locus, can recombine with the disease locus. In this study, we used a human ornithine aminotransferase (OAT) cDNA which detects OAT-related DNA sequences mapped to the same region on the X chromosome as that of the L1.28 probe to investigate the family with Norrie disease who exhibited the recombinational event. When genomic DNA from this family was digested with the PvuII restriction endonuclease, we found a restriction fragment length polymorphism (RFLP) of 4.2 kb in size. This fragment was absent in the affected males and cosegregated with the disease locus; we calculated a lod score of 0.602, at theta = 0.00. No deletion could be detected by chromosomal analysis or on Southern blots with other enzymes. These results suggest that one of the OAT-related sequences on the X chromosome may be in close proximity to the Norrie disease locus and represent the first report which indicates that the OAT cDNA may be useful for the identification of carrier status and/or prenatal diagnosis.

The authors recorded electroretinograms for 27 autistic patients and 20 age- and sex-matched healthy volunteers. Thirteen (48%) of the autistic patients demonstrated subnormal b-wave amplitudes, which may indicate abnormal retinal function. One patient was tested serially at two sites; his low b-wave amplitude did not vary over time or between the two sites. If this retinal finding can be confirmed at other laboratories and in larger samples of autistic patients, it might provide a marker for a specific subtype of autism.

Retinal abnormalities associated with hearing loss may be inherited alone or with additional manifestations. Environmental insults, such as rubella embryopathy, may also cause these abnormalities. We studied 13 patients with retinal abnormalities and hearing loss. Five had Usher's syndrome (retinitis pigmentosa and hearing impairment), one had crystalline retinopathy, two had associated enamel dysplasias, two had clumped pigmentary retinopathy, and three had Amalric-Diallinas syndrome. Our findings suggest considerable heterogeneity of syndromes involving retinal abnormalities and hearing loss.

Clinical studies and genetic linkage analysis in 64 members of a family with autosomal dominant congenital cataracts demonstrated intrafamilial variable expressivity and asymmetry between the two eyes. On the basis of 26 polymorphic phenotypic gene markers, linkage was excluded with the Duffy blood group (located on chromosome 1), haptoglobin (chromosome 16), and others. These data supported genetic heterogeneity of congenital cataracts as previous linkage assignments have included the pulverulent or Coppock cataract to chromosome 1 with Duffy and a posterior polar cataract to chromosome 16 with haptoglobin.

Meningococcal conjunctivitis is typically described as an acute purulent infection. An atypical case of mild catarrhal conjunctivitis occurred in a 19-year-old college student. The meningococci were identified as Neisseria meningitidis, group A, and were isolated from the throats of the patient and her roommate. The conjunctivitis responded rapidly to treatment with sodium sulfacetamide, and it was not treated systemically. A short review of the literature of meningococcal conjunctivitis is presented, and the current recommendation for prophylaxis is discussed.

Bateman, J. B. (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.) and F. Elizabeth White. Effect of relative humidity on the survival of Serratia marcescens in concentrated glycerol and sucrose solutions. J. Bacteriol. 85:918-926. 1963.-The effects of sucrose and glycerol upon the ability of Serratia marcescens to grow when restored to a normal medium after exposure to solutions of these substances were examined, with special attention to the prevailing thermodynamic activity of water in these solutions as a factor of supposed primary importance in influencing survival or death of cells. The data were notable for the absence of any zones of instability such as those found when the water activity is changed by exposure of washed cells to water vapor at controlled relative humidities (RH). The cells survived indefinitely at room temperature in concentrated sucrose solutions; in glycerol solutions of equilibrium RH values from 20 to 90, the first-order decay constants were about 0.03 to 0.1 hr(-1). These results, considered together with the contrasting phenomenon of narrow lethal humidity zones found in vapor-phrase equilibration experiments, were explained generally in terms of competitive interactions involving concentrated intrinsic and adventitious solutes, the cell water, and the organized structures of the cell, whose integrity was considered to depend ultimately upon the net effect of these various interactions.

The viability of washed moist cells of Serratia marcescens after storage has been measured in relation to variations in the prior treatment of the cells and in conditions of storage. The factors considered were: (i) water content during storage; (ii) method of arriving at water content (partial drying in vacuum or freeze-drying and addition of water); (iii) presence or absence of air during storage. Increasingly rapid decay occurs as the water content at which the cells are stored is diminished from above 90% to 20 or 30% ("critical" water content). It occurs in presence or absence of air and it occurs whether the final water content is approached by removal of water from wet cells or by addition of water to freeze-dried cells. The rate of decay during storage at 20 to 30% water is somewhat diminished by the presence of air ("protective" effect of air). As the water content is further reduced to less than 10%, the stability of cells stored in a vacuum approaches that of wet cells. In presence of air the reverse is true: the stability decreases until at less than 1% water, the decay rate is about as great as at the "critical" water content ("toxic" effect of air). Particularly rapid decay of S. marcescens at the "critical" water content has escaped attention in aerosol studies because accurate control of relative humidity (RH) in this region, RH 94 to 99%, is virtually impossible in such studies. On the other hand, values of decay rates referred to measured water contents are quite unreliable in the 20 to 80% RH zone because the corresponding variation of water content is too small to measure reliably. Thus data of the kind reported in this paper cannot be directly compared to the published results of studies of air-borne bacteria, although they are relevant to the practical question of air-borne infection in humid atmospheres.

In order to test a suggestion that inositol may take the place of water in maintaining the stability of desiccated cells, the reversible endothermic association of tobacco mosaic virus protein (TMVP) was studied turbidimetrically in presence of this substance. Its effect was to lower the temperature at which association takes place, the positive standard enthalpy and standard entropy of reaction both being increased by about 30%. The hypothesis of direct substitution of bound water by inositol at the site of macromolecular association leads to the contrary prediction that the association temperature would be raised. It is suggested that the observed effect of inositol may result from a conformation change in TMVP brought about by binding of inositol at positions adjacent to the site of reaction.