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L B Dahl

Publications and source records attributed to L B Dahl.

29 records · Page 2Linked to original sources
PubMed1988

Preparation of biologically intact radioiodinated hyaluronan of high specific radioactivity: coupling of 125I-tyramine-cellobiose to amino groups after partial N-deacetylation.

Hyaluronan was substituted with tyramine-cellobiose on amino residues exposed after hydrazinolytic N-deacetylation of the polysaccharide. Nonsubstituted amino groups were reacetylated, and the carboxylic hydrazides were removed by treatment with HIO3. The adduct was labeled with 125I before or after coupling to hyaluronan. N-deacetylation increased with prolonged pretreatment with hydrazine, which also reduced the chain length of hyaluronan. Hydrazinolysis for 30 min produced hyaluronan with Mr 2.2-2.9 x 10(5). This material was substituted with varying amounts of tyramine-cellobiose (from 1 per 20 to 1 per 130 disaccharides). Hyaluronan labeled in this way was recognized by Streptomyces hyaluronidase, hyaluronan affinity protein of cartilage proteoglycan, and receptors for specific endocytosis of hyaluronan in liver endothelial cells. Since tyramine-cellobiose is nondegradable and therefore is arrested intralysosomally at the site of uptake, turnover studies of hyaluronan can be easily carried out with this ligand.

Animals↗
PubMed1986

Serum levels of ampicillin and gentamycin in neonates of varying gestational age.

Serum concentrations of gentamycin and ampicillin were investigated at loading and in steady state in two groups of neonates, of 26-33 weeks and 34-40 weeks gestation. At loading the usual intravenous dose of gentamycin (2.5 mg/kg) was increased by 50%, the usual intravenous dose of ampicillin (50 mg/kg) by 100%. Gentamycin and ampicillin were administered subsequently at the same intervals, 12 h in the 34-40 weeks group, and 18 h in the 26-33 weeks group. Adequate serum levels were achieved from the first day of treatment. For practical reasons ampicillin and gentamycin can be administered subsequently at identical intervals also when the intervals exceed 12 h. The ideal dosing interval for gentamycin in very preterm neonates is 24 h. When treating small preterm and term neonates with an aminoglycoside, rapid serum concentration analyses should be available, and the treatment modified accordingly.

Ampicillin↗
PubMed1986

The molecular weight of sodium hyaluronate in amniotic fluid.

The molecular weight of sodium hyaluronate in human amniotic fluid was determined by gel chromatography. Pooled samples from 16 weeks of gestation exhibited a broad molecular weight distribution (Mw = 3 X 10(5); Mn = 6 X 10(4)). Samples taken at 40 weeks showed a low molecular weight fraction (M less than 10(5) presumably of fetal origin, and a high molecular weight fraction (M greater than 10(6) which varied considerably, indicating a nonfetal origin. No hyaluronate degrading activity was detected in the fluid. In a case of renal dysplasia, only minute amounts of hyaluronate were found. These findings are in accordance with a renal excretion of a low molecular weight hyaluronate from the fetus. In 12 cases with proven neural tube defects, there was no significant difference in hyaluronate level and molecular weight compared to normal controls.

Amniotic Fluid↗
PubMed1986

The catabolic fate of hyaluronic acid.

Part of the hyaluronic acid (HA) synthesized in peripheral tissues enters the blood circulation through the lymph. It is rapidly taken up by the endothelial cells in the liver (half-life in blood is 2.5-5.5 minutes) and degraded. Pure primary cultures of liver endothelial cells were obtained by a newly developed technique and used to follow the metabolism of the polysaccharide on the cell surface. At 37 degrees C the HA is effectively endocytosed and degraded to acetate and lactate. A radioassay specific for HA and sensitive in the nanogram range has been developed to follow the concentration of HA in serum. The normal level in man is 10 to 100 micrograms/l. Elevated serum levels of HA are seen in liver cirrhosis, rheumatoid arthritis and scleroderma indicating that both an impaired catabolism in the liver and an increased synthesis in the peripheral tissues can modify the HA level.

Animals↗
PubMed1985

Concentration and molecular weight of sodium hyaluronate in synovial fluid from patients with rheumatoid arthritis and other arthropathies.

The molecular weight distribution of hyaluronate (HA) in synovial fluid (SF) from 10 patients with rheumatoid arthritis (RA), from six patients with other joint disorders, and from five recently deceased persons without joint affections was investigated by a gel chromatographic procedure. A new and highly specific radioassay was used for determination of the HA concentration in the effluent from the chromatographic column, and this allowed analyses on 0.5 ml or less of untreated synovial fluid. The results confirmed the findings by others that the weight-average molecular weight (Mw) of HA in SF from patients with RA (4.8 X 10(6)) was similar to that in other joint diseases (5.0 X 10(6)) and moderately but significantly (p less than 0.001) lower than that of normal SF (7.0 X 10(6)). Furthermore, the molecular weight distribution of HA in the pathological SF was generally broad and varied considerably between individuals. The HA concentration in the pathological SF varied between 0.17 and 1.32 g/l, which is in accordance with previous reports and considerably lower than that of normal SF. Neither the nature of the arthropathy and the extent of the inflammatory process nor the pharmacological treatment had a tendency to influence the HA concentration in the SF, the mean molecular weight of HA, or its molecular weight distribution. Although the concentration of HA in SF drops in joint disease, the total amount of the polysaccharide is greatly enhanced. Also the amount of high molecular weight polysaccharide (Mw greater than 6 X 10(6)) is in excess in joint disease. The pathological state is therefore characterised not by lack of high molecular weight hyaluronate but by a dilution of it.

Adult↗
PubMed1980

Serum group I pepsinogens in children.

Serum group I pepsinogens (PG I) were determined by a radioimmunoassay method in blood drawn from premature and newborn infants, children of various ages, a control group of young healthy adults, and a group of women at delivery. Very low concentrations of PG I were found in blood of prematures and newborns, and there was no correlation between serum PG I in women at delivery and their newborn full-term infants. Serum PG I rose abruptly during the early months of life, but remained significantly reduced up to the age of 10 years. These findings are in agreement with those reports showing an increasing pepsin secretion during childhood, and thus indirectly lend support to the use of serum PG I as an estimate of gastric pepsin secretion.

Adolescent↗
PubMedDate not supplied

Does VLDL-LDL-cholesterol in cord serum predict future level of lipoproteins?

Lipoproteins were measured in 618 healthy, full-term newborns. Seventy-four with a VLDL-LDL-cholesterol above 1.3 mmol/l (50 mg/dl) at birth and 25 randomly chosen controls with VLDL-LDL-cholesterol 1.3 mmol/l or below at birth were followed up at age 2. Seventy-two (52 in the high VLDL-LDL-cholesterol group and 20 in the low VLDL-LDL-cholesterol group) were followed up at age 13. At age 2 mean total cholesterol was 5.48 mmol/l (SEM 0.10) in the children with a high VLDL-LDL-cholesterol at birth, compared to 4.69 mmol/l (SEM 0.17) in the children with a low VLDL-LDL-cholesterol at birth (p less than 0.001). A difference was still present at age 13 (4.74 mmol/l; SEM 0.11 versus 4.20 mmol/l; SEM 0.14; p less than 0.01). At age 13 apolipoprotein B was 0.74 g/l (SEM 0.02) in the children with a high VLDL-LDL-cholesterol at birth, compared to 0.65 g/l (SEM 0.02) in the children with a low VLDL-LDL-cholesterol at birth (p less than 0.01). Children with high VLDL-LDL-cholesterol at birth might be more liable to high lipoprotein serum levels later in life.

Apolipoprotein A-I↗