Biomedical subjects
Publications and source records attributed to M Lazar.
A case is described in which a right preretinal arterial loop was complicated by an obstructive episode, producing an altitudinal visual field defect. The mechanism of the occlusion of the retinal vascular loop and the pathogenesis of the associated vitreous hemorrhage are discussed.
Juvenile nephronophthisis and medullary cystic diseases are inherited kidney disorders leading to end stage uremia. As these diseases appear to be identical, they were grouped together in nephronophthisis-cystic renal medulla complex. Among its extrarenal manifestations, tapeto-retinal degeneration is the most frequent allied condition. This specific association of the renal and retinal conditions, suggesting a genetic background, is called hereditary renal-retinal dysplasia and is transmitted as an autosomal recessive trait. There are some variations in the type of the retinal degeneration in renal-retinal dysplasia and similar basic genetic mechanisms may results in Leber's congenital amaurosis, or retinitis pigmentosa, central retinal degeneration or stationary congenital night blindness. Pleiotropism seems to be responsible for the spectrum of these anomalies. Occasional expression in the heterozygous state by urinary concentrating disabilities or electroretinographic impairments were documented. The nature and pathogenesis of renal-retinal dysplasia remain a debated issue, but some evidence supports the possibility of an inborn error of metabolism causing the basic defects.
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Three patients with cystic fibrosis of the pancreas initially were seen because of optic neuropathy caused by a toxic reaction to chloramphenicol. The ocular symptoms were characterized by loss of visual acuity, central scotomas, red-green dyschromatopsia, and fundus changes. An increase in the latency of the occipital evoked potentials paralleled the visual impairment. A transient photopic decline in the red-light-elicited electroretinogram and the occurrence of Uhthoff's sign in the acute stage of the disease were observed. All visual impairment recovered partially or totally after the withdrawal of therapy with the drug.
Studies were carried out on the polymorphism of acetylcholinesterase (AChE, EC 3.1.1.7) in a neuroblastoma x sympathetic ganglion cell hybrid cell line (T28) and its parental clone (N18TG2). These cells contain the tetrameric (G4, 10S), dimeric (G2, 6.5S) and monomeric (G1, 4S) forms of AchE, but not the collagen-tailed A12(16S) form of the sympathetic ganglion. Three variants of these forms could be distinguished on the basis of their solubility properties: (i) secreted forms which do not interact with the detergent Triton X-100; (ii) cellular forms which may be solubilized in detergent-free buffer and which interact reversibly with Triton X-100; (iii) cellular forms which require detergent for solubility, and aggregate in its absence. By using a nonpenetrating inhibitor, we demonstrated that, in T28 stationary cells, the cellular G4 form is associated with the plasma membrane, whereas the G1 form is intracellular. During induction of AChE activity in T28 cells, the relative proportion of the G4 form increases, suggesting, in agreement with previous observations, that G1 is a metabolic precursor of G4. The evolution of AChE molecular forms released into the culture medium closely resembles that of the cellular forms. The preferential accumulation of the G4 molecules does not simply depend on the cellular level of G1. It is favoured by culture conditions which promote morphological differentiation, but does not require the actual extension of neurites. T28 cells as well as other neuroblastoma-derived cells appear to be useful experimental materials to investigate the regulatory mechanisms underlying the maturation of AChE globular forms.
A 7-year-old boy had an unusual association of median cleft-face syndrome, a characteristic physiognomy, unilateral retinal dysplasia, and bilateral retinal detachment. Despite surgical treatment to both eyes he became blind. The hereditary pattern operating in this complex disorder was found to be consistent with an autosomal dominant trait.
In a patient with juvenile nephronophthisis, sector retinitis pigmentosa was found as an extrarenal manifestation, establishing a hitherto undescribed variety of retinal degeneration occurring in this disorder. The retinal function in this case was identical with that in the classic type of sector retinitis pigmentosa, namely, subnormal ERG amplitudes but normal cone and rod implicit times. The range of the retinal findings and their autosomal recessive transmission are discussed. Paucity of information makes it difficult to elucidate the basic genetic defect operating in this condition.
6 cardiac patients were found to present various degrees of corneal involvement following systemic treatment with amiodarone. The clinical pattern of the keratopathy, its benign course and the pathophysiology are discussed. Lacrimal insufficiency or incomplete blinking seem to contribute to the severity of the keratopathy.
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Three families affected by juvenile nephronophthisis are described and genetically analyzed. The extrarenal manifestations of the disease include retinal findings such as congenital Leber amaurosis, retinitis pigmentosa and sector retinitis pigmentosa. Autosomal recessive transmission and the wide phenotypic spectrum are discussed. The variability in the retinal findings is explained by the presence of a pleiotropic gene with variable expressivity.
The occurrence of congenital oculomotor apraxia in two children of the same family is described. The improvement of the ocular dysfunction in the older sister gave some hints to the benign nature of the condition and its tendency to recover with age. The possible pathophysiological mechanism underlying this anomaly is discussed.
A boy of 2 had evidence of congenital retinal non-attachment. The mother had a veil like fold in one eye. There was no evidence of any systemic disorder. The inheritance might be X-linked recessive. Mild manifestations of the disease in the carrier mother may be more frequent than has been assumed and should be looked for.
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We studied the reversible cataractogenic effect of Miochol on rabbits' lenses. The experiments demonstrated that the lens opacities developing after the intracameral injection of Miochol were caused by the hypertonicity of the solution and not by a biochemical effect of the acetylcholine.
The numbers of clinically diagnosed, elevated nevocytic nevi (at least 2 mm in diameter) within 50 sq cm areas on the lateral and medial aspects of the arms of 1,000 subjects (age range 2 to 87 years) were compared. A total of 349 nevi was found on the lateral aspects and only 116 on the medial aspects of arms. Nevi were found on the lateral aspects of the arms in 23.4% (234) of the subjects and on the medial aspects in but 10.9% (109) of the subjects. These differences are highly significant in both men and women. Nevi were found in 30.2% (281) of the 930 whites but in only 9.1% (5) of the 55 blacks included in the study. Also, blacks did not show greater prevalence of nevi on the lateral as compared to the medial aspects of their arms. One explanation for the greater prevalence of nevi on the lateral over that on the medial aspects of the arms is that sunlight plays a role in the induction of acquired nevocytic nevi.
The iris involvement in generalized carcinomatosis is less frequent than that of the ciliary body and choroid; its point of interest is that it might constitute the presenting sign of the general disease. The case of a 43-year-old man who had a metastasis of an anaplastic bronchus carcinoma in the iris and died of metastases 3 months after the appearance of the iris tumor, despite adequate chemotherapy, is reported.