Search PubMed⌕ Search

Biomedical subjects

U Mayer

Publications and source records attributed to U Mayer.

At least 109 records · Page 6Linked to original sources
PubMed1982

[A rare form of optical, choroidal and retinal dysplasia combined with an occipital encephalocele].

Report on the case of a female infant born with an occipital encephalocele and colobomas of the optic disc, chorioid, and retina. These clinical signs together with respiratory disturbances suggest a Joubert syndrome and a Pfeiffer syndrome. The differential diagnosis of these syndromes is discussed. An analysis of the clinical data indicates a genetic risk of 25% for further siblings.

Choroid↗
PubMed1982

[Clinical picture and inheritance of ocular symptoms in arteriohepatic dysplasia (author's transl)].

Systematic examination of four children suffering from arteriohepatic dysplasia and of members of their families revealed with diminishing frequency, the following symptoms: icterus episcleralis, posterior embryotoxon, gray-yellowish precipitations in the retina, microphthalmos, corectopia with rudimentary coloboma of the iris, xanthomatosis retinae and atrophy of the optic nerve. The parents of the children presented with minor symptoms such as dysplasia iridis, arcus lipoides and hyperlipemic vascular signs in the retina. Differential diagnostic considerations suggest a hereditary disease, the pathogenesis of which is not completely clear.

Abnormalities, Multiple↗
PubMed1982

[Morphological changes induced by the addition of various antibiotics to lens epithelium cultures].

Morphological and biochemical characteristics of surviving and cultured bovine lens epithelia in TCM 199 with 20% calf serum have been described several times in the authors previous publications. The injurious action of different substances in vitro was observed: gentamicin, penicillin and tetracycline. Even in common concentrations there were side effects of various types and degrees. This could be important in washing donor material or the anterior chamber.

Animals↗
PubMed1982

[Remarkable clinical findings relating to the differential diagnosis of noninflammatory exophthalmos].

Communication concerning the diagnosis and treatment of noninflammatory vascular exophthalmos: (1) 12-year-old boy suffering from a 4 mm proptosis on the left eye, and a hemangioma of the left upper lid. Computerized tomography showed an orbital tumor whose dilated vessels extended into the foramen opticum. Since the patient was amblyopic the treatment was merely cosmetic, consisting in diathermic puncture of the lid hemangioma. -(2) 45-year-old woman suffering from an axial proptosis of the right eye. Computerized tomography showed a retrobulbar tumor compressing the optic nerve. Surgical removal of a cavernous hemangioma by the neurosurgeon led to restitutio ad integrum. -(3) 8-year-old boy with intermittent exophthalmus on the left. No tumor detectable in routine examinations. External carotid angiography finally revealed an arteriovenous shunt between the A. maxillaris and the V. orbitalis superior. -These three descriptions of patients suffering from exophthalmus illustrate currently available possibilities of ophthalmologic and neurosurgical collaboration for diagnosis and treatment.

Child↗
PubMed1981

Late spreading of excitation in the lateral geniculate nucleus following visual deafferentation is independent of the size of retinal lesions.

Late spreading of excitation occurs in the lateral geniculate nucleus following partial retinal lesions. The extent of spreading remained the same when reducing the size of the lesions to one fifth. This is incompatible with the idea that the spreading could be caused by displacement of normal cells into the deafferented area as a consequence of transneuronal volume reduction.

Afferent Pathways↗
PubMed1981

Time-dependent decrease in the extent of visual deafferentation in the lateral geniculate nucleus of adult cats with small retinal lesions.

Small, round photocoagulator lesions of 3-6 degrees (0.6-1.2 mm) diameter were placed nasally on the retina of adult cats. Histological controls proved the complete destruction of all retinal layers within the lesions. Changes in lesion size by shrinkage of the retinal scar did not exceed 0.1 mm or 0.5 degrees. At different times after photocoagulation, single cells were recorded in layers A and A1 of the contralateral lateral geniculate nucleus (LGN) with tungsten microelectrodes. Acute lesions of this size completely deafferented single LGN cells in layer A whose receptive field (RF) area was within the lesion. Thirty days and more after coagulation, light-excitable cells were detected in the originally deafferented LGN region, with RFs in the immediate surround of the retinal lesion. The spontaneous activity and light excitability of these neurons were altered. The representation of 3-4 degrees retinal lesions at 20 degrees horizontal eccentricity was found to be completely filled in by excitation in the LGN. Excitation had spread from the unsevered parts of the retina into the region of deafferentation. Single cells with signs of multiple activation from more than one border region of the retinal lesion were occasionally detected.

Animals↗
PubMed1981

[Septo-optical dysplasia: oligosymptomatic form (author's transl)].

It is reported on a nine year old boy with the oligosymptomatic form of the septo-optical dysplasia de Morsier: congenital nystagmus with nearly complete loss of visus due to a hypoplasia of the opticus-nerve of both sides, growth retardation (dwarfism) because of STH-deficiency and lack of the gonadotropins. The septum pellucidum is present. The cause of this embryologic malformation within the prosencephalon is not known.

Abnormalities, Multiple↗
PubMed1980

A functional sign of reorganization in the visual system of adult cats: lateral geniculate neurons with displaced receptive fields after lesions of the nasal retina.

High-intensity photocoagulator lesions placed nasally to the optic disc one eye destroyed all retinal layers and led to visual deafferentation of the lateral part of layer A in the contralateral lateral geniculate nucleus (LGN) of adult cats. The retino-geniculate topography was determined with vertical tungsten microelectrode penetrations through LGN layers A and A1 before and at different times after photocoagulation. Before the 20th day a border of light excitability was found in layer. A corresponding to the normal projection of the lesion onto the LGN. Deviations from the normal topographical organization were evident 30 days and later after photocoagulation. Cells were recorded within the deafferented part of layer A near to the border of deafferentiation which had receptive field (RF) centers displaced by more than two degrees of visual angle with respect to the normal retinotopy. During formation of the retinal scar no identifiable points on the retina were displaced in the same direction as the RF centers. The histological control of the retinal lesions proved that there was no potentially excitable tissue left to account for a spread of excitation into the lesion. Latency measurements after electrical stimulation of the optic tract and the visual cortex suggested a retinal input and a projection into the visual cortex for the LGN cells with displaced receptive field centers. RF center displacements up to five degrees at the border of the lesions indicated a lateral spread of excitation within the LGN up to 250 micron beyond normal.

Animals↗
PubMed1980

[Changes in the cat's visual system following retinal lesions. A functional reorganization in the mature central nervous system (author's transl)].

Layers of the lateral geniculate nucleus (LGN) of mature cats were completely or partially deafferentated by precisely defined photocoagulation of the retina. Single neuron recordings were performed with microelectrodes from an experimentally modified layer and compared with neurons from a normally innervated layer in the same animal. The spontaneous activity of cells after monocular deafferentation was severely reduced in the beginning and increased subsequently without reaching normal values within ten weeks. At this time the pattern of excitation and inhibition after light stimulation of the nondominant unsevered eye had completely changed. Twenty-seven days and later after coagulation of a part of the nasal retina light-excitable cells with displaced receptive fields were found in the LGN in the border region of the partial visual deafferentation. This indicated a lesion-induced lateral expansion of excitation by up to 200 microns within the LGN. Small, round retinal lesions initially caused a complete visual deafferentation of a certain region in the LGN. After 30 days and later visual excitation from the normally innervated surrounding was observed in cells which were not light-excitable during the first days after coagulation. Thus, while the retinal lesion itself did not substantially change, its representation within the LGN was distinctly reduced. The results indicate lesion-induced reorganization in the subcortical visual system of the adult cat. This might enable the system to a certain degree of compensation after loss of visual inputs. The transferability of these results to human pathophysiology has to be critically considered.

Animals↗
PubMed1980

Comparative investigations of catalase activity in different ocular tissues of cattle and man.

As previously published, ocular catalase activity was measured by Warburg's respirometer, the examined material being taken from the local slaughterhouse and keratoplasty-donor eyes. The results were given in microliter O2 per mg soluble protein (Biuret's solution) and showed an extensive parallelism between human and bovine eyes: They were in a decreasing order of catalase activity, i.e., conjunctiva > retina > vitreous > sclera > iris > choroid > cornea > aqueous humor > serum > lens. In the latter, catalase activity was a sensitive indicator of aerobic metabolism. Oxidative processes in the vitreous merit more consideration.

Animals↗
PubMed1978

[Comparative investigations concerning the influence of pilocarpine and aceclidine on the glucose consumption of surviving ocular tissues (author's transl)].

Conservative glaucoma therapy repeated during a whole lifetime raises the question of medicamentuous tolerance. Recently, cultivation of normal lens epithelia and of iris tissue has made possible determination of metabolic functions with and without application of different medicaments. Preceding experiments revealed a diminution in glucose consumption by these tissues after addition of pilocarpine. Comparative studies show 0.25 g/100 ml medium to be maximum concentration of aceclidine allowing cellular survival. With this dilution, the glucose metabolism of lens epithelia was much more sensitive to aceclidine than to pilocarpine. This was less true for iris tissue. Accordingly, the lens of an aceclidine-treated patient requires careful observation.

Animals↗
PubMed1978

[Partial trisomy 2p due to a familial translocation 2/6. Cytogenetic and clinical case with special reference to ophthalmologic changes].

A translocation 2/6 inherited for 3 generations is described. The propositus, carrier of a partial trisomy 2p, showed multiple morphological anomalies of which microphtalmus and persistance of primary vitreous body were of particular interest. Based on a comparison of this with seven other patients in the literature, the most characteristic clinical symptoms of partial trisomy 2p are concluded to be the following: abundant lanugo at birth, glabella prominence, anteverted nares, dermatoglyphic anomalies, and malformations of the eyes.

Abnormalities, Multiple↗
PubMed1978

[Hydroxychinoline- and zinc-treated acrodermatitis enteropathica and electroretinographic findings (author's transl)].

A meanwhile 13 years old boy had to be treated by hydroxychinolines for a severe acrodermatitis enteropathica since his 1st year of life. At the age of 5 years he showed visual deterioration by atrophia optici. Dose reduction and application of different halogen substitutions were tried. Finally, it was daily oral zinc application and continuous control of the serum zinc level which made disappear all cutaneous and mucous symptoms. At an unchanged ophthalmoscopic status, there occurred a slight raise of vision, an enlargement of peripheric campus and a normalization of the electroretinographic potentials.

Acrodermatitis↗
PubMed1978

[Retinographic alterations in different forms of congenital cataracta (author's transl)].

In a follow-up study of patients suffering from congenital cataract, particular attention was paid to the electroretinogram. Besides hereditary lens opacifications and rubella embryopathy, galactosaemia and spontaneous idiopathic hypoglycemia occurring in children and infants were examined. The question, how much biochemical factors can influence the ERG, is becoming more important.

Cataract↗