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Biomedical subjects

M Larsen

Publications and source records attributed to M Larsen.

At least 163 records · Page 9Linked to original sources
PubMed1989

Lens fluorescence in relation to metabolic control of insulin-dependent diabetes mellitus.

The correlation of blue-green lens fluorescence to the metabolic control of insulin-dependent diabetes mellitus was studied in 36 patients in whom the level of glycosylated hemoglobin A1c (HbA1c) had been followed from the onset of diabetes. Good metabolic control (22 patients, all with mean HbA1c levels, less than 7.0% and, thus, low blood glucose concentrations) was associated with less lens fluorescence and a higher lens transmittance than poor metabolic control (14 patients, all with mean HbA1c levels, greater than 9.7%). It appears that in diabetes, an increase in lens fluorescence and a decrease in lens transmittance are delayed by good metabolic control, and that the determination of lens fluorescence provides information about the long-term control of diabetes.

Adolescent↗
PubMed1989

Effect of antihypertensive treatment on blood-retinal barrier permeability to fluorescein in hypertensive type 1 (insulin-dependent) diabetic patients with background retinopathy.

The effect of antihypertensive treatment on blood-retinal barrier leakage of fluorescein in background retinopathy was studied in nine hypertensive Type 1 (insulin-dependent) diabetic patients suffering from nephropathy. The patients were investigated before and after 7 (3 to 13) months of treatment with captopril (n = 8; 25 to 100 mg daily) and a diuretic, either frusemide (n = 4; 80 to 200 mg daily) or bendrofluazide (n = 2; 2.5 mg daily). Retinal function was assessed by fundus photography, fluorescein angiography, vitreous fluorometry, and renal function by glomerular filtration rate, and albuminuria. The antihypertensive treatment induced a significant reduction (p less than 0.05) in: blood pressure from 152/97 +/- 14/8 mmHg to 134/82 +/- 11/6 mmHg; blood-retinal barrier leakage of fluorescein from 2.4 +/- 1.1 to 1.4 +/- 0.5.10(-7) cm/second; albuminuria from 1391 (range: 168-4852) micrograms/min to 793 (range: 35-2081) micrograms/min. Glomerular filtration rate declined from 88 +/- 15 to 78 +/- 23 ml.min-1.1.73 m2 (0.05 less than p less than 0.10). The metabolic control of the patients as reflected by their blood glucose and HbA1c levels remained stable during the study. Our study suggests that systemic blood pressure elevation contributes to the abnormal blood-retinal barrier permeability to fluorescein characteristically found in diabetic background retinopathy and that this abnormality can be reversed during antihypertensive treatment.

Adult↗
PubMed1989

Two hundred intrauterine exchange transfusions in severe blood incompatibilities.

Two hundred intrauterine exchange transfusions were performed under local anesthesia in 107 cases of blood incompatibilities (60 fetuses with severe anemia and 47 with hydrops). Under sonographic guidance, depending on fetal and placental position, an optimal puncturing site was selected along the umbilical vein: placental insertion, fetal insertion, or fetal intraabdominal segment. Tests were immediately performed to confirm fetal origin of blood obtained and estimate hemoglobin level. Blood used for exchange transfusion was compatible with maternal blood and had a hematocrit value of 75%. Exchange transfusion was continued until a hemoglobin level of 16 gm/dl was reached. This procedure was first associated with intraperitoneal transfusions and was subsequently used independently once a month to maintain an adequate hemoglobin level. In 4 fetuses with hydrops, antenatal regression of this sign was observed in 33 cases (70.2%). Overall outcome of 107 fetuses after exchanges was 84 living neonates (78.5%), 15 deaths in utero, and eight neonatal deaths. The survival rate was 91.6% for fetuses without hydrops and 61.7% for those with hydrops. The advantage of exchange transfusion appears to be rapid and efficient correction of anemia with elimination of incompatible fetal red blood cells.

Birth Weight↗
PubMed1989

Time-resolved fluorescence properties of fluorescein and fluorescein glucuronide.

The use of fluorescein as a tracer in the study of the blood-ocular barriers is complicated by the metabolic production of fluorescein monoglucuronide, the excitation and fluorescence spectra of which overlap with those of fluorescein. Time-resolved fluorescence measurements provide a means of detecting the two substances in a mixture. Fluorescein and fluorescein glucuronide have different fluorescence lifetimes, 4.0 nsec and 2.3 nsec, at 37 degrees C and pH 7.35. Hence the two substances can be distinguished from the biexponential fluorescence decay in the mixture. The lifetimes are identical in buffered water, in hyaluronic acid and in human vitreous in vitro. The method is suggested for estimation of fluorescein and fluorescein glucuronide in the human vitreous in vivo. The time-resolved and steady state fluorescence anisotropies, the fluorescence lifetimes and the quantum yields strongly suggest that binding of fluorescein or fluorescein glucuronide to hyaluronic acid or other macromolecules in the human vitreous is weak, if present at all, and that static quenching of fluorescence does not occur in the vitreous.

Fluorescein↗
PubMed1989

Fluorescein and fluorescein glucuronide in vitreous: fluorescence and binding properties in vitro.

The total and ultrafiltrable fluorescence were measured after disodium fluorescein and fluorescein monoglucuronide were added to aliquots of human and porcine vitreous, and to aliquots of phosphate buffer with and without 0.2% sodium hyaluronate. No significant binding or quenching of F or FG by vitreous or sodium hyaluronate could be found, indicating that vitreous binding is not a source of error in vitreous fluorometry.

Animals↗
PubMed1988

Fluorescein and fluorescein glucuronide in plasma after intravenous injection of fluorescein.

After intravenous injection of fluorescein the time-course of the plasma concentrations of fluorescein (F) and fluorescein glucuronide (FG) was studied in 18 insulin-dependent diabetics with various degrees of nephropathy, and in two non-diabetic subjects. Fifteen minutes after injection the molar concentrations of free (non-protein bound) F and FG were almost identical. After one hour the concentration curve integrals of the two substances were of the same magnitude. There was, however, considerable interindividual variation. In diabetic patients with renal insufficiency an increase was found in both integrals, the F integral being less increased (27%) than the FG integral (44%). It appears from the variation in absolute and relative concentrations of F and FG that a separate determination of the two fluorophores in plasma is desirable, when F is used by intravenous administration as an indicator of blood-ocular barrier function. Previous observations of an increase with time after injection of the free fraction of plasma fluorescence are explained by the finding of a higher free fraction of FG (34%) than of F (11%) and a change in relative concentrations of the two fluorophores.

Adult↗
PubMed1988

[Bilirubin-albumin-binding function of 2 human albumin preparations (placental and plasma). Comparison of their efficacy in the icteric premature infant].

Two albumin preparations obtained by Cohn fractionation of either plasma of blood donors (plasmatic albumin) or human placental blood (placental albumin) were studied in vitro and in vivo regarding their bilirubin-binding function. Analysis of this function during the industrial processing of the two preparations indicated that alcoholic fractionation and, to a lesser extent, stabilizers, were responsible for the decrease of (a) the association constants between albumin and bilirubin, (b) bilirubin-binding capacity of albumin. Unexpectedly, improvement of bilirubin-binding parameters was observed after the final heating stage. Stabilizers were reversibly bound as suggested by a further improvement of binding function seen after a brief contact of the preparations with red blood cells. The changes were similar for the two preparations. Fifty-one sick premature hyperbilirubinemic neonates were randomly infused either with placental or plasmatic albumin (1.5 g/kg). Albuminemia, bilirubinemia, erythrocytic bilirubin, unbound bilirubin (peroxidase method) were evaluated before and 3 hours after infusion. Improvement of bilirubin-binding parameters was frequently observed but without clear-cut relation with change in bilirubin/albumin molar ratio. No difference was noted between the two albumin preparations. In spite of a decrease of their association constants with bilirubin, the two albumins retained a high binding potency for bilirubin in vivo.

Bilirubin↗
PubMed1987

Fluorescein and fluorescein glucuronide in the vitreous body of diabetic patients.

Fluorescein (F) and fluorescein glucuronide (FG) were determined in the vitreous of four diabetic patients by a double-filter slit-lamp fluorophotometric technique. Determinations were performed 60-80 min after i.v. injection of fluorescein. F and FG were also determined in plasma ultrafiltrate 5, 15, 30, 60 and 120 min after injection by high-pressure liquid chromatography. The concentration of FG in the vitreous was 3 times that of F. After correction for plasma concentrations of FG higher than those of F, the penetration index of FG through the blood-retinal barrier was found to be twice the penetration index of F. This is not what would be expected if passive transport alone were involved. Accordingly, it is suggested that active transport mechanisms contribute to the movement of F and FG across the blood-retinal barrier.

Blood-Retinal Barrier↗
PubMed1987

Lens autofluorescence in diabetes compared with the level of glycosylated hemoglobin A1c.

The autofluorescence of the crystalline lens has been measured by an ocular fluorophotometer in two comparable groups of patients with insulin-dependent diabetes mellitus. One group has had a high level of HbA1c since the onset of diabetes (mean 10.1 per cent) and the other group a very low level (mean 6.5 per cent). The group with low HbA1c during the disease period showed a significantly lower lens fluorescence than the group with high HbA1c.

Diabetes Mellitus, Type 1↗
PubMed1987

Fluorophotometric evaluation of ocular barriers and of the vitreous body in the aphakic eye.

8 aphakic patients were studied with fluorophotometry and 3-mirror examination of the vitreous body one month after cataract extraction. 4 were extracapsular with posterior chamber pseudophakos (ECCE) and 4 were intracapsular with anterior chamber pseudophakos (ICCE). A mathematical model is used to calculate blood-ocular fluorescein permeability (P) and vitreous diffusion coefficient (D) from fluorophotometric scans. All 30-minutes scans in the ECCE group and 2 in the ICCE showed a profile resembling that in phakic eyes, and P- and D-values were calculated. In the remaining two patients from the ICCE group scans showed rapid filling of the vitreous cavity with fluoroscein and calculations could not be made. Clinical examination showed vitreous detachment in these two eyes whereas the others had a normal vitreous structure evaluated by 3-mirror examination. It is shown that fluorophotometric readings can be made in both intra- and extracapsularly operated eyes. Rapid mixing of the dye in the vitreous cavity is seen in relation to vitreous detachment.

Aged↗
PubMed1987

Waterborne paints. A review of their chemistry and toxicology and the results of determinations made during their use.

This work presents information on the composition of waterborne construction paints used in Denmark, data from determinations of chemicals evaporating from paints applied with a brush or roller, and the toxicology of these chemicals. Seven product types were selected to illustrate the composition of the paints. Measurements at two workplaces were used as models for the work environment during painting. Evaporating chemicals were collected on Tenax TA and analyzed with capillary column gas chromatography after thermal desorption. In smudging work, waterborne paints may result in skin irritation and/or sensitization when safety precautions are not taken. Irritation of the mucous membranes may be expected if airing is not sufficient. This irritation may lead to headache mediated by trigeminal nerve stimulation. No other health hazards (eg, brain damage) are expected. The available information indicates that waterborne paints are a clear improvement over traditional paints which use white spirit as the main solvent.

Air Pollutants, Occupational↗
PubMed1987

[Ante-partum administration of preventive treatment of Rh-D immunization in rhesus-negative women. Parallel evaluation of transplacental passage of fetal blood cells. Results of a multicenter study carried out in the Paris region].

1,969 non immunized rhesus negative primiparous women were followed up in 23 maternity units in the geographical region of Paris. 1,882 could be retained to study antepartum protection and 1,884 to study transplacental passage of fetal blood cells. Two groups were defined according to whether they were born in even or uneven years, so that: 955 were the "control" group who delivered 590 rhesus D positive infants, and 927 were the "treated" group who delivered 599 rhesus D positive infants. The "control" group were used as controls at the 28th and 34th weeks of pregnancy, while the "treated" group received two injections of anti-D immunoglobulin given on the same dates after taking the necessary tests. Immunological testing at the time of the delivery and after the delivery showed that 7 women had become Rh D immunized in the "control" group whereas only one in the "treated" group. This difference, which is statistically significant, confirms the results of other authors about the efficiency of antepartum rhesus disease prevention. The incidence of immunisation during or immediately after the first pregnancy in women who had no previous story of blood transfusions or of terminations of pregnancy is 1.11%, which is a figure relatively low as compared with studies of series carried out in North America, but close to those carried out in other European centres. When primipara of all categories are lumped together the frequency rises to 1.5%. A study of the passage of fetal red blood cells into the maternal circulation shows that at the 29th week of pregnancy out of 1,884 cases there were 5.5% positive kleihauer tests, without a large volume of blood being detected and at the 34th week of pregnancy when 957 tests were carried out, 7% were positive with one of them being of a massive transfusion of blood from the fetus to the mother, which was life-threatening for the fetus. It may be that the incidence had been under-estimated and that the positive results in the two groups, control and treated, show that there is a statistically significant difference that demonstrates that antepartum treatment in the trial has eliminated a worthwhile percentage of positive kleihauer tests which arose from the transfusion of small quantities of blood.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical Trials as Topic↗
PubMed1986

Carriers of X-linked retinitis pigmentosa. A fluorophotometric determination of the permeability of the blood-retinal barrier.

The blood-retinal barrier permeability to fluorescein was studied in a single family with X-linked retinitis pigmentosa by an elaborate vitreous fluorophotometric method. Affected males showed a ten times increase of permeability compared with normals. In a group of seven obligate carriers the mean permeability was significantly increased by 45% compared with the mean permeability in a group of normals. Five of the seven carriers had permeabilities higher than the normal mean permeability + 2 SD, while two carriers had a permeability within the normal mean +/- 2 SD. Thus, this study supported that carriers of X-linked retinitis pigmentosa show deterioration of the blood-retinal barrier. However, the phenomenon is not present in all carriers and the permeability cannot be used as a completely safe indicator of the carrier state.

Adolescent↗
PubMed1986

Prognosis in glomerulonephritis. II. Regression analyses of prognostic factors affecting the course of renal function and the mortality in 395 patients. Calculation of a prognostic model. Report from a Copenhagen study group of renal diseases.

The course of the renal function and mortality were analysed in 395 patients with biopsy-proven glomerulonephritis (GN), using Cox's proportional hazards model. Seventeen clinical, biochemical and histopathological parameters were analysed for prognostic information. The patients were grouped according to their serum creatinine levels. Increase in serum creatinine, decrease in serum creatinine, cure and death were used as endpoints for the analysis. Caplan Meyer curves were made for 7 transitions between different groups and the variables were reduced by a step-wise procedure to a final model. Thirteen of the variables considered offered significant prognostic information (p less than 0.05) for at least one of the transitions. Short duration of disease, young age, non-nephritic urinary sediment and preceding streptococcal infection were predictors of cure. Extracapillary, membranoproliferative and unclassifiable GN, old age and arterial hypertension predicted increase in serum creatinine in patients with low serum creatinine, while male sex, short duration of disease and pathological electrocardiogram favoured a further increase in patients with high serum creatinine. A later decrease in serum creatinine was signified by a preceding streptococcal infection, short duration of disease, absence of arterial hypertension and low urinary protein excretion. Death without uremia was predicted by high age, connective tissue disease and extracapillary GN. Using these parameters and the models, it is possible to make a prognostic forecast for the individual GN patient. Examples of such a forecast are described.

Adult↗