Biomedical subjects
Publications and source records attributed to A Ringvold.
An epidemic follicular conjunctivitis affecting teen-aged females has been studied. Moraxella lacunata was isolated from 11% of the patients, a frequency far above the rate found in other types of chronic conjunctivitis. The condition is suggested to be the chronic follicular conjunctivitis (Axenfeld) due to Moraxella lacunata.
High-performance liquid chromatography on a Supelcosil LC-HN2 analytical column in weak anion exchange mode has allowed separation of ascorbic acid, in less than 5 min, from other interfering substances in serum and aqueous humour. UV monitoring at 254 nm enables ascorbic acid to be detected at 20 pmol level. A method for determination of ascorbic acid concentration in serum and aqueous humour is described, and values from 10 cataract patients are reported.
Three days after UV-irradiation of the rabbit cornea, there was epithelial loss and stromal oedema, which was most prominent in the anterior 1/4. Many of the keratocytes in this region were killed. The inner 3/4 of the stroma showed a large number of round or oval cells with nuclear fragmentation and abnormal inclusions. These cells were taken to be seriously, though reversibly harmed keratocytes. The tissue structure was normalized within one week, and the UV-induced changes seem to refer to the 290-350 nm interval.
Serum, aqueous humour, and lens ascorbic acid levels were determined by high-performance liquid chromatography in cataract-, closed-angle glaucoma-, and aphakic patients. The total number of 108 patients were subdivided into different groups. In several groups the pre-operative serum and aqueous amounts were tested, whereafter patients in some groups were loaded with ascorbic acid orally. Finally, a second test was performed on samples taken during operation. It turned out that the ascorbic acid concentration mechanism in cataractous eyes needed more than 12 h for maximum reaction on the loading stimulus. The slow reaction is surprising compared to other species, and it may reflect an affection of the secretory process itself in this disease.
The present report describes the history of a 66-year-old man suffering from recurrent retinal haemorrhages combined with retinal vascular tortuosity. He also developed a non-chromaffin paraganglioma in the neck, and the coincidence of these two rare diseases is discussed.
A hexagonal pattern is formed by the apical aspects of the corneal endothelial cells. However, by electron microscopy of surface-parallel sections it can be seen that the basal part of these cells has a highly irregular shape with deep indentations and high ridges. Near the Descemet membrane numerous cytoplasmic processes are tangled together in a bewildering pattern. A few of these processes are exposed to the posterior surface, where they may be seen as small cell-like areas delineated by cell borders. The hexagonal apical pattern of the endothelium is related to minimum total length of the intercellular apical sealing. This pattern may develop by a minimizing process with analogy to the minimum surface formation of soap bubble film.
ABO-blood groups and Rh-factor (D-antigen) were determined in 236 patients with POAG, 104 simple and 132 capsular glaucoma. There was a statistical significant difference in the ABO-distribution between the two glaucoma subgroups, and also between the capsular-group and our control material. The simplex-group did not differ from the control material in this respect. For the Rh-group (D-antigen) no differences were found, neither between the two glaucoma subgroups nor between each of them and a reference material.
A 70-year-old man with a seronegative rheumatoid arthritis showed some peculiar lamellar crystalline deposits mainly at the Descement/endothelial level in both eyes. Serum protein analysis revealed a monoclonal gammopathy with increased amounts of IgG and K-light chains along with traces of the latter in the urine. Corneal biopsy was not available, but electron microscopy of the conjunctival specimen demonstrated crystalline deposits within the endoplasmic reticulum of plasma cells lying within the connective tissue. This material is supposed to be of protein nature. It seems reasonable that the conjunctival deposits are identical to those seen in the cornea by slit-lamp examination, and it is also suggested that they represents paraprotein aggregates. After treatment with melphalan (Alkeran) and prednisone systemically, the corneal deposits decreased over a period of 9 months with corresponding improvement of the visual acuity.
Rabbit cornea epithelium was exposed to UV-radiation for 15 min from a distance of 50 cm, and specimens were studied after 1/2, 1, and 3 h, respectively. The following changes occurred: 1) Reduced number of the large impressions or the full-thickness holes of the superficial cells. 2) Partly rejected cells. 3) Numerous small plasma membrane defects. This investigation shows plasma membrane defects at an early stage after the exposure, and this may be the locus for the initial damage.
Explore the source record for details and available documents.
Four cases of homocystinuria with lens luxation have been examined. As judged from the plasma amino acid pattern, they all responded well on pyridoxine treatment. Two of them discontinued the treatment on their own, and one of these died at the age of 17 years. The lens luxation progressed in one case despite adequate treatment. Scanning electron microscopy of one lens revealed partly broken zonules, abnormal zonular attachment, and a spongy appearance of the capsule proper. Hoping that adequate treatment will reduce more serious complications such as thromboembolism in these patients, it is concluded that an early diagnosis largely depends on the ophthalmologist, who should perform the silver-nitroprusside test, specific for homocystinuria, in all patients with non traumatic lens luxation.
The rabbit cornea endothelium has been studied with specular and scanning electron microscopy after exposure with a commercially available ultraviolet lamp. The animals were plased 50 cm from the source, and most experiments were run with a 20 min exposure time. In the specular microscope, the endothelium revealed numerous circumscript reflex-free areas, which were observed from 4 days up to 8 months after the irradiation. A wide variety of changes were found in the scanning electron microscope. One day after the exposure the cells showed indistinct outlines, and they were bulging into the anterior chamber. In some regions the pattern was dominated by marked grooves preferentially along the cell demarcations, whereas other regions showed rough surfaced cells because of cytoplasmic projections and grainy deposits. At the 3 days stage there was a marked pleomorphy, and some cells were on their way to being rejected. After one week the cobblestone appearance of the endothelium was about to decline. Partly rejected cells were still common. In addition, distinct, ringshaped local impressions occurred imitating the previous described grooves. This phenomenon along with some single endothelial cells studied with microvilli were the abnormal findings 8 months after the damage. It is concluded that although ultraviolet radiation is largely absorbed in the cornea, the threshold dose for damage of the endothelium is not beyond those used for practical purpose. The endothelium was surprisingly resistant towards repeated radiation damage.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The iris vascular bed of eyes with pseudoexfoliation syndrome has been studied with electron microscopy. Two of the eyes suffered from painful glaucoma, whereas the third showed normal intraocular pressure. The following changes were observed: (1) deposits of pseudoexfoliation material lying adjacent to the endothelial wall; (2) thin vessel basement membrane, sometimes even interrupted; (3) extreme reduction of vessel lumina through increased volume of the endothelial cells; (4) fenestration of the endothelial wall. It is suggested that the iris neovascularisation in eyes with pseudoexfoliation syndrome is due to an obstruction of iris vessels causing tissue hypoxia.
The absorption of ultraviolet radiation in the cornea of rabbit, cat, guinea pig, and rat has been studied. It turned out that about 80% of incident radiation is absorbed at the 290 nm wavelength limit in rabbit and cat, whereas the absorption is considerably lower in guinea pig and rat. In a model experiment based on conditions in the rabbit cornea epithelium, it is shown that the ascorbic acid in these cells is roughly responsible for ultraviolet ray absorption of the same order as proteins and nucleic acids in the 250-290 nm spectral range. This implies that for radiation below 290 nm wavelength also the ascorbic acid should be regarded as a potential target substance which may mediate photophthalmic damage to the tissue. The low absorption of the ascorbic acid compared to the other two components above 290 nm, indicates that the ascorbic acid contributes less in photophthalmic development due to solar radiation.
Studies on the ultraviolet ray absorption in the aqueous humour of rabbit, cat, monkey, guinea pig, and rat showed marked species differences. In the rabbit aqueous the ascorbic acid, the proteins, and some amino acids (tyrosine, phenylalanine, cystine, and tryptophane) are together responsible for the total absorption, and a very great part of it refers to the ascorbic acid content. Accordingly, species with significant amounts of ascorbic acid in the aqueous (monkey, rabbit, guinea pig) have a greater absorption capacity towards ultraviolet radiation than species (cat, rat) lacking this substance. This effect of the ascorbic acid may contribute in protecting the lens against the most biotoxic ultraviolet rays. It seems that the ascorbic acid concentration is highest in the aqueous of typical day animals and lowest in species being active in the dark, indicating a correlation between the aqueous' ascorbic acid level and the quantity of incident light on the eye. The possible significance of changed aqueous ultraviolet ray absorption in the pathogenesis of human cataract development is discussed.
One case of aphakic retinal detachment with increased intraocular pressure is described. Overnight the intraocular pressure fell abruptly to non-measurable values, and simultaneously the detachment had advanced to the optic disc border. The hypothesis is formulated that decreased intraocular pressure in eyes with retinal detachment is brought about because intraocular fluid is leaking out of the eye through a subretinal route to the perioptic connective tissue. Additional support for this posterior aqueous outflow is obtained from clinical studies showing that maximum hypotony is reached when the detachment has advanced to the optic disc border.