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Biomedical subjects

D G Cogan

Publications and source records attributed to D G Cogan.

At least 91 records · Page 5Linked to original sources
PubMed1975

Structure of the muscles of the upper eyelid.

The human and monkey orbicularis muscle has fibers that are more uniform in size and structure than those of rectus muscles. They have distinct myofibrils, a moderate number of mitochondria, and a well-developed transverse T-tube system. The levator muscle also has relatively uniform fibers, but the myofibrils are less distinct than those of the orbicularis. Especially noteworthy is the unusual arrangement whereby Muller muscle arises directly from the undersurface of the levator muscle, causing an intimate intermingling of smooth and striated fibers. Muller muscle then inserts on the tarsus, whereas the levator muscle extends by an aponeurosis into the septa of the orbicularis muscle. In surgical specimens from patients with ptosis, the levator fibers show varying degrees of abnormality, whereas Muller fibers are normal.

Adolescent↗
PubMed1975

Cholesterosis bulbi: the ocular abnormality known as synchysis scintillans.

Review of inpatient records at the Massachusetts Eye and Ear Infirmary for ten years and the inpatient and outpatient records at the Children's Hospital Medical Center for eight years revealed no diagnosed cases of synchysis scintillans. The pathology reports from the Ophthalmic Pathology Laboratory at the Massachusetts Eye and Ear Infirmary for the last ten years revealed 12 eyes with cholesterol crystals in the vitreous cavities or subretinal spaces, or both. All were blind, long-term damaged eyes; there were no vitreous cholesterol crystals observable clinically. This study corroborates previous reports and suggests that synchysis scintillans occurs only in severely damaged, blind eyes not visible to observation. Both the current concept and terminology of synchysis scintillans are inaccurate. Cholesterosis bulbi is a more appropriate term. Cholesterol crystals are clinically different from asteroid bodies since the former occurs only in a damaged, functionless eye.

Adolescent↗
PubMed1975

Immunologic study of nonsyphilitic interstitial keratitis with vestibuloauditory symptoms.

We studied four patients with the clinical entity of nonsyphilitic interstitial keratitis and vestibuloauditory symptoms to determine whether immunologic abnormalities play a role in its pathophysiology. There was no evidence of alteration in nonspecific cell-mediated or humoral immunologic status of any of the patients studied. Three of the four patients had W-17, a histocompatibility antigen that occurs in 3 to 10% of the normal population. All four patients had increased cell-mediated immunity against normal allogenic corneal antigens compared to normal control subjects. There seems to be no apparent generalized alteration of the immune system in this syndrome.

Adolescent↗
PubMed1975

Vascular occlusions in the eye from cardiac myxomas.

Vascular occlusion in the eyes from cardiac myxomas was diagnosed in two cases, belatedly in one and not until after death in the other. Suspicion of a myxomatous origin should be aroused by the combination of unexplained retinal (or choroidal) vascular disease occurring with multifocal neurological symptoms and with systemic symptoms suggesting atypical subacute bacterial endocarditis. The first patient had unilateral retinal artery occlusion by embolic material believed to have been myxomatous. Removal of the cardiac myxoma resulted in disappearance of this material (although the eye remained blind). The second patient who had had evidence of retinal artery occlusion in the clinical course of her multisystemic disease was found at autopsy to have extensive myxomatous involvement of the posterior ciliary arteries and of the choroidal arteries of both eyes and of the retinal artery in one eye.

Adolescent↗
PubMed1975

Central retinal artery occlusion.

Data regarding the etiology and subsequent course of 54 patients with an occlusion of the central retinal artery included the following: of 44 patients over 40 years of age at the time of the central retinal artery occlusion, eight (18%) had cerebrovascular accidents, but only two patients (5%) had a stroke clearly related to the vessels involving the affected central retinal artery. Five patients (11%) had occlusive disease of the ipsilateral internal carotid artery; two of these had cerebral involvement later or simultaneously. Ten of the older patients had cardiac valvular disease and presumed embolic occlusion of the central retinal artery. Associated medical disorders were common. Of the ten patients under 40 years of age, six occlusions were secondary to atrial myxoma, mitral insufficiency with Marfan's syndrome, polycythemia, hypercoagluopathy, hypertension, and orbital compression. Four had no apparent etiology at onset and were in good health many years later.

Adolescent↗
PubMed1975

Lysosomes and melanin granules of the retinal pigment epithelium in a mouse model of the Chediak-Higashi syndrome.

The origin of giant granules in the retinal pigment epithelium of the beige mouse was investigated with electron microscopy and ultrastructural histochemistry. These granules were found to contain melanin and acid phosphatase. Apparently they arise from fusions of primary lysosomes with melanin granules which are already enlarged from multiple fusions among melanosomes. Therefore, the giant granules are not primary lysosomes, nor are they simply enlarged melanin granules as suspected from light microscopic studies. A deficiency of primary lysosomes in the pigment epithelium results, suggesting a defect in intracellular digestion similar to that found in the leukocytes of Chediak-Higashi patients and several animal models. Affected humans probably have defective digestion in their retinal pigment epithelium also; which could impair the renewal process for rod outer segments. Thus, Chediak-Higashi patients may show an increased susceptibility to light damage due not only to hypopigmentation, but to defective intracellular digestion, as well.

Acid Phosphatase↗
PubMed1971

Congenital anomalies of the retina.

Review of 50 histopathologic cases and a number of clinical cases of congenital retinal anomalies has permitted classification under the following headings: 1) Coloboma-orbital cyst--"anophthalmos" group due to aberrant closure of the embryonic fissure; 2) Retinal fold-central stalk-detachment group comprising a series that varies from simple retinal folds to total retinal detachment and anomalous stalk formation. Cases of the 13-15 trisomy syndrome constitute a special subgroup in this rubric; 3) Retrolental fibroplasia, due to hyperoxia of premature infants, is manifest by "dragged" disks and gliovascular proliferation with occasional detachment; 4) Persistent hyaloid system is occasionally associated with mild anomalies of the retina; 5) Massive gliosis of the retina is usually a hamartomatous manifestation; 6) Congenital absence of ganglion cells occurs with cerebral maldevelopment and 7) Congenital absence of the photoreceptors is the congenital form of retinitis pigmentosa.

Abnormalities, Multiple↗