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Biomedical subjects

I Immonen

Publications and source records attributed to I Immonen.

At least 55 records · Page 3Linked to original sources
PubMed1993

Retinoids increase urokinase-type plasminogen activator production by human retinal pigment epithelial cells in culture.

PURPOSE: To examine the effect of two retinoids, all-trans-retinoic acid (tretinoin) and all-trans-9-(4-methoxy-2,3,6- trimethylphenyl)-3,7-dimethyl- 2,4,6,8-nonatetraenoic acid (acitretin) on the production of plasminogen activators and plasminogen activator inhibitors by human retinal pigment epithelial cells in culture. METHODS: Cultures of human retinal pigment epithelial cells were incubated with either of the retinoids at a concentration of 1 microM for 24-72 hours. The media were assayed using solid-phase immunocapture assays and zymography. RESULTS: Both retinoids caused a twofold to sevenfold increase in urokinase-type plasminogen activator in the medium. The effect was seen after 24 hours in culture and was further augmented up to 72 hours. No significant amounts of tissue-type plasminogen activator were detected. The plasminogen activator inhibitor activity was unaffected by the retinoids. Proliferation and morphology of retinal pigment epithelial cells were also unaffected by the retinoids in incubations for up to 72 hours. CONCLUSIONS: Retinoids profoundly affect the extracellular proteolysis of retinal pigment epithelial cells in culture. This effect may be related to the differentiation-inducing activity of retinoids seen in other cell types, often connected with changes in extracellular proteolysis. It is possible that retinoids may modulate dedifferentiation, proliferation, and migration of retinal pigment epithelial cells seen in vitro, as well as in the pathogenesis of retinal disease.

Acitretin↗
PubMed1992

Radiotherapy of malignant melanoma of the uvea with I-125 seeds.

Nineteen patients with malignant uveal melanomas were treated with I-125 applicators. There were 10 males and 9 females with a median age of 61 years (range 42-76). The tumour was located in the choroid in 12 eyes and in the choroid and ciliary body in 7 eyes. The size of the tumours was 7-18 mm in maximal basal diameter (median 12), 5-16 mm in minimal basal diameter (median 10), and 5.5-15 mm in thickness (median 8.5). The volume of the tumours was 123-1890 mm3 (median 540). All tumours were classified as large (T3). For the irradiation, a computer program, which calculates three-dimensional dose distribution of I-125 seeds in gold plaques, was developed. By modifying the seed positions, activity and the orientation, patients can be treated individually. Iodine-125 emits low energy photons, ideal for intraocular tumour therapy and tissue. Extra-ocular tissue located behind the applicator can be completely shielded by a 0.5 mm gold layer. The dose at the apex of the tumour ranged from 30 to 120 Gy (median 93). The treatment time ranged from 44 to 600 h (median 235). Preliminary results are good. After a median follow-up of 6 months, the tumour growth has been arrested in all eyes and in 10 eyes the tumour has decreased in size.

Adult↗
PubMed1992

Retinal pigment epithelial cells secrete urokinase-type plasminogen activator and its inhibitor PAI-1.

Secretion of plasminogen activators and their inhibitors was examined in cultures of human retinal pigment epithelial (RPE) cells. The methods employed were zymography and reverse zymography, solid-phase immunocapture assay, metabolic labeling followed by immunoprecipitation, and immunofluorescence. The results showed that these cells produce urokinase-type plasminogen activator (u-PA) and a plasminogen activator inhibitor (PAI) which is immunologically and biochemically similar to PAI-1. Tissue-type plasminogen activator activity (t-PA) was not detected, but we detected small amounts of t-PA in an inactive complex with inhibitor in RPE cell-conditioned media. We conclude that RPE cells have the potential to utilize u-PA-catalyzed plasminogen activation which is subject to regulation by PAI-1. These results may have a bearing on the pathogenesis of proliferative retinal diseases.

Antibodies, Monoclonal↗
PubMed1992

An immunohistochemical and prognostic analysis of cytokeratin expression in malignant uveal melanoma.

A group of 52 patients with malignant uveal melanoma treated by primary enucleation in 1977-1979 was studied to determine the frequency of immunoreactivity for cytokeratins (CK) in primary and metastatic melanoma, the CK types present, and the prognostic significance of CK expression. By immunohistochemistry, monoclonal antibody (MAb) V9 to vimentin reacted with all 52 formalin-fixed, paraffin-embedded primary tumors and all 31 metastases from 11 patients. MAb CAM 5.2 to CK 8 and 18 reacted with 20 and MAb CY-90 to CK 18 with 25 primary melanomas, whereas MAb KS-B17.2 and MAb CK5 to CK 18 labeled 8 and 6 tumors, respectively. Antibodies to CK 13 and CK 19 each labeled single cells in one specimen, and other CK types were not detected. In 6 primary melanomas, only a few tumor cells were immunopositive for CK 8 and 18, but in 17 cases up to one quarter, and in 2 tumors more than one quarter, of them were labeled. The positive cells were spindle, epithelioid, or intermediate in shape, and tended to be more frequent in mixed than in spindle cell melanomas. MAbs CAM 5.2 and CY-90 did not react with any of the 16 liver metastases, but labeled 7 of 15 other metastases. Metastases were somewhat more common when the primary tumor was immunoreactive for CK 8 and 18, apparently because CKs were more frequent in mixed cell melanomas. Although CK expression is of diagnostic significance and can denote low levels of epithelioid differentiation, it is not an independent prognostic factor in malignant uveal melanoma.

Adolescent↗
PubMed1991

Immunohistochemical demonstration of cellular fibronectin and tenascin in human epiretinal membranes.

The occurrence of fibronectin, cellular fibronectin and tenascin was studied immunohistochemically in epiretinal membranes from 5 patients with retinal detachment and 3 patients with macular pucker, and in preretinal membranes from 3 patients with proliferative diabetic retinopathy. Positive immunofluorescence for these proteins was seen in all specimens studied. The presence of cellular fibronectin suggests that local production of fibronectin occurs in these membranes. The expression of tenascin, an extracellular matrix glycoprotein, originally found to modulate organosenesis in tendinous and glial tissue, suggests that this glycoprotein also participates in the regulation of cellular growth in these membranes.

Adolescent↗
PubMed1991

Transcleral contact krypton-laser photocoagulation of the retina in rabbits.

Transcleral contact retinal krypton laser photocoagulation of the retina was studied in rabbit eyes. The laser application was performed under indirect ophthalmoscope visual control with indentation of the sclera by the laser probe. Retinal lesions were produced with powers ranging from 0.2 to 0.3 W and application times between 1 and 2 sec. The lesions were studied histologically 2, 5, 10, 12, 20, 30 and 70 days after treatment. Histopathological examination of the lesions showed damage of mainly the outer retinal layers in light lesions, and to all layers of the retina in the more intense lesions. No scleral damage was observed in the light lesions, whereas transient oedema of the inner sclera was seen in the intense lesions. Studies with enucleated rabbit eyes showed that indentation of the sclera by the laser probe substantially decreased the power needed to produce a retinal lesion. It is concluded, that when used with scleral indentation, transscleral krypton laser photocoagulation of the retina can be performed with minimal damage to the sclera.

Animals↗
PubMed1990

Culture of retinal pigment epithelial cells from subretinal fluid.

Culture of cells from subretinal fluid (SRF) was performed using 29 SRF samples obtained at retinal reattachment surgery. Proliferating cells were found in 58.6% of the samples studied. The cells were of retinal pigment epithelial (RPE) origin, as evidenced by their brown pigmentation in primary culture and their positive immunostaining for cytokeratins 8/18. The age of the patients did not affect the proliferative capacity of the cells. Proliferating cells were present in all samples from eyes with proliferative vitreoretinopathy (PVR) of grade C1 or more. In primary culture the cells had a fibroblast-like morphology, resembling that of ordinary RPE cells exposed to the vitreous. We conclude that the SRF of many patients with PVR contains viable proliferating RPE cells and that SRF offers a new source of RPE cells for studies on the pathogenesis of PVR.

Adolescent↗
PubMed1989

Peripheral retinal angiomalike lesion and macular pucker.

We interpreted clinical data on five eyes with preretinal macular fibrosis (macular pucker) in association with a solitary angiomalike lesion in the peripheral retina. One angioma was associated with von Hippel-Lindau disease, and the others were regarded as acquired sporadic angiomas occurring in otherwise healthy persons. Regression of the vascular mass occurred as a result of transscleral cryopexy in four eyes and by argon laser in one eye. After treatment, the macular pucker was stabilized, but regression of the preretinal membrane did not occur. The visual acuity improved after cryotherapy in one eye, and in two eyes visual improvement occurred after vitrectomy and membrane removal.

Adult↗
PubMed1989

Contact lens wear is associated with the appearance of plasmin in the tear fluid--preliminary results.

We determined biochemically the plasmin concentration in tear fluid from 50 externally healthy eyes and from 49 eyes during contact lens (CL) wear. After cessation of CL wear, samples were collected again from 41 of the 49 eyes. Plasmin was detected more frequently (P less than 0.0001) in the CL-wearing group (75.5%) than in the control group (20%). After the cessation of CL wear (3-21 days), the frequency of plasmin detection in tear fluid decreased significantly (P less than 0.0006) but was still higher (39%) than in the control group. We conclude that the occurrence of plasmin in tear fluid is correlated with CL wear. The proteolytic activity of plasmin may contribute to the development of corneal epithelial pathology associated with CL wear.

Contact Lenses↗
PubMed1989

Acute retinal necrosis syndrome treated with vitrectomy and intravenous acyclovir.

Acute retinal necrosis syndrome in a healthy 32-year-old man was treated successfully with systemic acyclovir and corticosteroids in combination with vitrectomy, 360 degrees encircling band and transscleral cryocoagulation. Herpes simplex virus antibodies were detected in the vitrectomy aspirate supporting the current view that acute retinal necrosis is caused by viruses of the herpes group.

Acute Disease↗
PubMed1989

Tissue-type plasminogen activator in subretinal fluid.

The plasminogen activation system is quantitatively the major mechanism of extracellular proteolysis. To evaluate its role in retinal detachment, plasmin and plasminogen activators were measured in subretinal fluid (SRF) from 12 eyes of twelve patients. Plasmin was detected in 5 eyes (mean 6.26 micrograms/ml, SD = 3.7 micrograms/ml). Tissue-type plasminogen activator was present in 5 eyes (mean activity 0.33 IU/ml, SD = 0.24 IU/ml) but the activity did not associate with the plasmin activity in all of the SRF samples. Urokinase-type plasminogen activator was not detected in SRF. We conclude that the plasmin system has been activated in SRF in some eyes with retinal detachment with tissue-type plasminogen activator as the predominant activator. Plasmin in SRF may enhance dispersion of pigment epithelial cells into the subretinal space and the vitreous, a phenomenon seen frequently in eyes with retinal detachment.

Adult↗
PubMed1988

Multiple evanescent white dot syndrome.

Multiple small infiltrates deep in the retina were found in three previously healthy patients aged 21-28 years in association with a mild non-specific acute infection. In two patients the lesions were uniocular, in one patient both eyes were affected. Both posterior pole and midperiphery were involved. In two cases the optic disk was slightly swollen. Due to macular lesions the visual acuity on admission varied from 0.1 (6/60) to 0.6 (6/10). On fluorescein angiograms the lesions were initially hypofluorescent and later slightly hyperfluorescent. No causative agents were discovered. All lesions resolved in 4-8 weeks without treatment, leaving faint pigment dispersion or, more commonly, no visible scars, and the visual acuity recovered to 1.0 (6/6).

Adult↗
PubMed1988

Elevation of tear fluid plasmin in corneal disease.

Plasmin concentration was determined in tear fluid from 76 eyes showing corneal epithelial disorders, such as corneal ulcers and erosions due to trauma or contact lens wear. Nearly 70% of the eyes with corneal disease had plasmin in their tear fluid, whereas plasmin was present in only 20% of the eyes in a control group of 50 eyes. Re-examination of the plasmin positive control eyes revealed conjunctival bacterial growth or mild subclinical viral infection in most cases. We conclude that plasmin is released into the tear fluid in the presence of corneal or conjunctival lesions or infections, suggesting a pathogenic role of plasmin in these disorders. The significance of the occurrence of plasmin in tear fluid during corneal wound healing is discussed.

Adult↗
PubMed1988

Visual results and social rehabilitation after cataract surgery. A retrospective comparison of the effect of non-IOL and IOL surgery.

This report examines the changes that occurred in the post-operative visual and social function of patients with cataract when the hospital responsible for cataract treatment (roughly 1000 cataract extractions per year) shifted from non-IOL to IOL techniques. Visual function and vision-dependent social performance were compared retrospectively in 116 patients, 53 of whom had undergone cataract extraction without IOL implantation, and 63 of whom had been treated by IOL implantation. Patients with no IOL had the possibility of using extended-wear contact lenses if unable to tolerate aphakic spectacles. Visual results and social rehabilitation were good with both techniques, and there was no significant difference in vision-dependent social performance between the groups. The quality of vision and patient satisfaction with surgery were better in IOL patients. It appears that, once vision is restored by surgery and contact lenses are available, post-operative function in patients is determined by factors other than the type of cataract surgery. However, the shift to IOL surgery brings about improved quality of vision and patient satisfaction.

Aged↗
PubMed1988

Economic evaluation of cataract surgery: a comparison between IOL and non-IOL techniques.

Using a sample of 116 patients, 53 of whom had undergone cataract extraction without IOL implantation, and 63 of whom had been treated by IOL implantation, a retrospective evaluation of differences in economic effects was performed. The use of non-IOL technique was cheaper for the hospital, but the overall costs for society were soon higher, mainly as a result of the significantly higher costs of obtaining contact lenses and spectacles in the non-IOL group. The longer we expect cataract surgery patients to live post-operatively the greater will be the difference in favour of using the IOL technique. The estimated annual savings to society for every 875 patients operated would be from FIM 5 million to FIM 26.5 million if non-IOL technique was used and from FIM 10.5 million to FIM 28.5 million with IOL surgery. Cataract surgery, and especially with IOL technique, seems to be an operation resulting in substantial savings to society.

Cataract Extraction↗
PubMed1987

Acute transverse myelopathy successfully treated with plasmapheresis and prednisone in a patient with primary Sjögren's syndrome.

We report a case of acute transverse myelopathy in a patient with primary Sjögren's syndrome of 3 years duration. Our patient's acute transverse myelopathy developed within 1 week and resulted in complete paraparesis below the mamillary level. Extensive laboratory investigation ruled out viral, bacterial, and fungal etiology, Guillain-Barré syndrome, poliomyelitis, and multiple sclerosis. At diagnosis, treatment was initiated immediately with prednisone (80 mg/day) and plasmapheresis, which was performed as a first-aid measure. Improvement was noted as early as 10 days after the start of therapy. Within 5 1/2 months of the first symptoms of paralysis, the patient walked without difficulty and returned to her normal activities. A causal relationship between plasmapheresis/prednisone therapy and recovery has not been proven but merits further consideration.

Acute Disease↗
PubMed1987

Effect of tranexamic acid on postvitrectomy haemorrhage in diabetic patients.

Thirty one diabetic patients were prospectively randomized for treatment with or without tranexamic acid during vitrectomy for proliferative diabetic retinopathy. No significant difference in the occurrence of postoperative haemorrhage in the treated and untreated group was observed (37%/28% during the 1st postoperative week, and 25%/40% during the 2nd-4th postoperative weeks, respectively). The final visual result was similar in both groups.

Adolescent↗