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Biomedical subjects

M V Andersen

Publications and source records attributed to M V Andersen.

12 recordsLinked to original sources
PubMed1996

Scanning Laser Ophthalmoscope microperimetry compared with Octopus perimetry in normal subjects.

Simultaneously performed ophthalmoscopy and perimetry by microperimetry using the Scanning Laser Ophthalmoscope eliminates some of the classical problems involved in transformation techniques in perimetry such as: optical distortions, unsteady fixation and alignment. Almost all reports published on microperimetry have addressed chorioretinal diseases, with only a few patients in each study. No reports have studied the normal values of this method. To evaluate the reliability of microperimetry, 30 healthy subjects-10 subjects from each of the age group: 40-49 years (male/female ratio: 4/6), 50-59 years (m/f ratio: 5/5) and 60-69 years (m/f ratio: 5/5)-were repeatedly examined with microperimetry and automatic perimetry performed by the Octopus macular program M1. The results of the present study of microperimetry show that the standard deviation of the interindividual variance component was 1.36, that the standard deviation of the intraindividual variance component was 0.94 and that a test result obtained by microperimetry in any of the two locations studied can be related to a test result obtained by Octopus M1 in the same location.

Adult↗
PubMed1995

Differential diagnosis of choroidal melanomas and nevi using scanning laser ophthalmoscopical indocyanine green angiography.

Fluorescein angiography is one of several standard ancillary diagnostic techniques in the evaluation of suspected malignant choroidal melanoma. Indocyanine green choroidal angiography has improved visibility of the choroidal circulation in comparison with fluorescein angiography. Studies concerning the use of indocyanine green angiography in the differentiation between nevi and melanomas have been few and the results inconclusive. A case of a choroidal melanoma (verified by histopathological examination) and a nevus in the same eye is documented by fluorescein and indocyanine green choroidal angiography performed by scanning laser ophthalmoscopy. This modality may be considered in the evaluation of a suspected malignant choroidal melanoma.

Aged↗
PubMed1994

Proton-lactate cotransport in the apical membrane of frog retinal pigment epithelium.

We studied lactate- and pyruvate-dependent proton transport across the apical membrane of frog RPE. The epithelium was mounted in a modified Ussing-chamber that allowed measurement of transepithelial potential and resistance while intracellular pH was measured with either intracellular microelectrodes or a pH-sensitive dye, 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). To estimate the rate of lactate influx from the change in intracellular pH, we used the NH4 pulse technique to measure intracellular buffering capacity and its dependence on intracellular pH. We found that the buffering capacity was 16 mM at pH1 = 7.28, and that it increased as intracellular pH decreased. Intracellular pH was monitored with the tissue bathed in nominally HCO3-free (Hepes buffered) Ringer. The perfusate on the apical side of the epithelium was then changed to a Ringer that contained between 5 and 100 mM lactate or pyruvate. When 10-100 mM lactate or pyruvate was added to the apical bath the cells acidified by 0.05-0.50 pH units. For each of these acidifications, the initial acid influx into the RPE cells was calculated from the intracellular buffering capacity and the initial rate of intracellular acidification. These influxes were plotted as functions of the concentrations of lactate or pyruvate and this relationship was analysed using Michaelis-Menten kinetics. The Km values were: 33 +/- 5 mM for lactate and 9 +/- 3 mM for pyruvate. There were no differences in the rates of acid influx caused by L- or D-lactate. The rates of acidification caused by 50 mM apical L-lactate were reversibly reduced by 56% after apical administration of probenecid (2 mM), and irreversibly reduced by 63% after apical administration of the SH-reagent mersalyl acid (2 mM). These results indicate the presence of a proton-lactate cotransport system in the apical membrane of the frog RPE.

Animals↗
PubMed1994

Central retinal artery occlusion in a patient with Fabry's disease documented by scanning laser ophthalmoscopy.

Fabry's disease, angiokeratoma corporis diffusum, is an X-linked inborn error of glycosphingolipid metabolism due to lack of activity of the lysosomal enzyme, alpha-galactosidase A, resulting in progressive intracellular deposition of neutral glycosphingolipids in various tissues, including vascular endothelial - and smooth muscle cells. Occlusions of the retinal vessels are rare. We present a case of central retinal artery occlusion in a 25-year-old male with Fabry's disease, documented by fluorescein- and indocyanine green angiography performed by scanning laser opththalmoscopy.

Adult↗
PubMed1991

Changes in the vitreous body pH of pigs after retinal xenon photocoagulation.

In an unpaired study, in vivo measurements of pH in vitreous were performed on normal pig eyes and pig eyes treated with retinal xenon photocoagulation. In one group (n = 7) the mean vitreal pH was 7.29 at a mean arterial pH of 7.41. In the other group (n = 8) two to three weeks after retinal xenon photocoagulation, a significant increase in mean vitreal pH of 0.06 to 7.35 (P less than 0.01) was observed at a similar arterial pH. Induced hypercapnia resulted in a decrease in pH vitr. and induced hypocapnia in an increase, with similar changes in pH art. The respiratory pH changes were similar in the two groups. These findings allow one to assume that, as a result of retinal photocoagulation, a change in the retinal metabolism is induced, either by a change in the relationship between aerobic and anaerobic metabolism or as a result of a general reduction of the metabolic activity.

Acidosis, Respiratory↗
PubMed1990

Reduction of complement activation in rheumatoid arthritis by steroid treatment.

Patients with severe active active rheumatoid arthritis (RA) have higher than normal plasma concentrations of the complement C3 split-product C3d, indicating increased complement activation. Treatment with steroids reduced plasma C3d levels in these patients. Ten patients with classic or definite RA and high disease activity were studied during six days of treatment with steroids. The C3d plasma concentrations declined in a dose-related manner with an increase in daily prednisolone dosage. However the statistical significance of this relationship did not seem to be high enough to validate the use of serial C3d estimations to monitor changes in disease activity in RA patients during short-term steroid treatment.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Cerebral thromboembolism among young women and men in Denmark 1977-1982.

In the period 1977-1982, the Danish National Patient Register recorded 1000 cases of cerebral thromboembolic attacks among women 15-44 years of age, and 971 cases among men of the same age. Cerebral infarction accounted for 70% of cases and transient ischemic attacks (TIA) for the remaining 30%. By analysing this material we found an average age-adjusted incidence rate of cerebral thromboembolism of 14.4/100.000 among men and 15.5/100.000 among women. The incidence rates rose rapidly with increasing age. Women aged 15-34 had significantly higher incidence rates of brain infarction and TIA compared to those of men of the same age. This was reversed in the age group 35-44. The magnitude of the ratio between the female and the male mean incidence rates by increasing age corresponded exactly to the age distribution of the use of oral contraceptives in Denmark. The relative risk for developing cerebral thromboembolism among users of oral contraceptives was estimated to be 3.2-6.5. The mortality in male patients with brain infarction was 3.3% and in females 1.7%. The mean duration of stay in hospital was 8.8 days for TIA and about 26 days for cerebral infarction. Sixteen percent of men and 13.6% of women had hypertension during their stay.

Adolescent↗