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Biomedical subjects

J Sebag

Publications and source records attributed to J Sebag.

67 records · Page 4Linked to original sources
PubMed1983

The induction of retinal detachment.

The induction of retinal detachment is dependent upon several factors whose relative importance remains controversial. These factors are retinal breaks, often associated with vitreous traction, inertial forces and changes in chorioretinal adhesion. Retinal breaks may be classified as holes, tears and dialyses. The relation to the vitreous base is an important prognostic indicator. Once a retinal break has occurred, inertial forces disturb the normal vitreo-retinal association. At that point, the development of a clinical detachment also depends upon loosening of the normal chorioretinal adhesion. Myopia and aphakia are important predisposing factors. The presence of preretinal membranes is a precipitating factor for recurrent retinal detachment. The high success rate of current surgical techniques (85 per cent) is mainly related to a better understanding of the mechanisms leading to retinal detachment.

Adhesiveness↗
PubMed1982

Pseudochalazion of the upper lid due to hard contact lens embedding -- case reports and literature review.

Two cases of pseudochalazion formation secondary to hard contact lens embedding are reported. In all previously reported cases a lump, swelling, mucopurulence, and ptosis were the most common presenting symptoms. Embedding usually occurred concave to the globe in the supratarsal region. The cases reported herein are unique in that the location of one lens was beneath the tarsal conjunctiva, and in the second case there was spontaneous release of the lens after four months of embedding.

Adolescent↗
PubMed1977

Effect of temperature on bacterial killing by serum and by polymorphonuclear leukocytes.

Bacterial killing by serum alone and by polymorphonuclear )PMN) leukocytes was studied at 37 degrees C and compared with killing at 39 and 41 degrees C. The test organisms for serum killing were Staphylococcus aureus 502A (serum resistant) and Escherichia coli O14 (serum sensitive). The organisms used in PMN killing tests were Streptococcus pneumoniae type 29 and E. coli O86.S aureus was not killed by serum alone at any temperature. Changes in temperature did not affect the rate of serum killing of E. coli O14 for the first 60 min, but by 90 and 120 min there was a discrepancy with continued killing at 37 degrees C, but no further killing at 39 and 41 degrees C. PMN phagocytic killing of the pneumococcus was enhanced at 39 degrees C compared with 37 degrees C, and phagocytic killing of E. coli O86 was decreased at 41 degrees C when compared with 37 degrees C. Therefore, it appears that under certain circumstances fever may aid the host PMNs in destroying organisms, whereas under other circumstances it may interfere with such destruction.

Blood Bactericidal Activity↗
PubMed1975

Decision-making in clinical practice: application of predictors, indicators and indices to the medical history obtained by a self-administered questionnaire.

A theoretical description of predictors, indicators, and health indices was presented in an earlier paper (Hall and Sebag, 1974). The application of predictors, indicators and health indices--including dynamic health indices--to anamnestic data obtained by a self-administered questionnaire is presented herein. Predictors and indicators showed a varying degree of 'decision-making significance' in the 122 questions examined. The health index distinguished between diagnosed individuals and those receiving no diagnosis(es). The dynamic health index was found to reflect changes in the health status of an individual over a period of time.

Decision Making↗
PubMed1975

Relationship between work environment and anamnestic health status. Use of predictors, indicators and indices for the evaluation of medical and environmental factors.

Experience with computerized medical record systems in handling medical data in hospital and health screening environments has led to the development of a new approach to the evaluation of medical data. Predictors and indicators quantify the "information value" of medical data and can, theoretically, do so for all types of data. This paper describes the methodology and presents the results obtained when the technique was applied to the anamnestic data of the medical history and environmental data about the conditions in the work environment. Over 4,000 individuals who underwent multiphasic health screening were used as a data base for this study. From these 4,000 persons 3,164 were used for the calculation of anamnestic predictors and indicators and 1,013 for the environmental predictors and indicators. Anamnestic environmental indices were calculated upon 77 test individuals so as to correlate the association and dependence of the two indices.

Environmental Exposure↗
PubMedDate not supplied

Diabetic retinopathy. Pathogenesis and the role of retina-derived growth factor in angiogenesis.

Diabetic retinopathy results from a combination of systemic and ocular abnormalities. Vasodilation, basement membrane pathology, microaneurysms, abnormal blood flow and tissue oxygenation, connective tissue abnormalities, and retinal ischemia are all components of early diabetic retinopathy. The pathogenesis of neovascularization is discussed with respect to the effects of vasodilation, vascular leakage, vitreous changes, and retinal ischemia. The evidence supporting Michaelson's hypothesis that a chemical messenger from the retina provides the stimulus for neovascularization is cited. The sequence of events involved in angiogenesis are cellular and basement membrane changes, endothelial cell migration, endothelial cell proliferation, and vessel formation. The experimental evidence in support of a role for retina-derived growth factor as a mediator of these cellular events is reviewed.

Basement Membrane↗
PubMedDate not supplied

Interfaces.

There are important similarities in molecular composition and structural organization of the interface between the vitreous and retina and that between the retina and retinal pigment epithelium. It is striking that the two most common causes of severe vision loss in the western world involve neovascularization at these interfaces; i.e., proliferative diabetic vitreo-retinopathy at the vitreo-retinal interface and exudative age-related macular degeneration at the retina-retinal pigment epithelium interface. Improved knowledge of the physiology of these interfaces will lead to a better understanding of the effects of aging and diseases, especially those that involve neovascularization. Such advances will no doubt result in new treatment strategies offering more effective therapy, and, even more importantly, perhaps providing prevention from these devastating causes of blindness.

Bruch Membrane↗