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Biomedical subjects

A Nilsson

Publications and source records attributed to A Nilsson.

At least 469 records · Page 26Linked to original sources
PubMed1986

Midazolam-fentanyl anesthesia for major surgery. Plasma levels of midazolam during prolonged total intravenous anesthesia.

The water-soluble benzodiazepine midazolam was used along with fentanyl and pancuronium in a totally intravenous anesthetic technique for hysterectomies. Midazolam was given as a 0.3 mg X kg-1 bolus dose followed by constant rate infusion of 0.25 mg X kg-1 X h-1. Plasma midazolam concentrations were measured during the anesthesia. The technique provided excellent conditions for surgery, with pulse rate and blood pressure under good control and without any recall of the peri-operative period. A disadvantage was early respiratory depression, which necessitated administration of naloxone to make extubation possible. This was attributed to the proportionally large amount of fentanyl used. Drowsiness during the first postoperative hours was also pronounced.

Adult↗
PubMed1986

Some observations made by intracellular recordings in a primary astrocyte culture and a glioblastoma '138 MG'.

Intracellular recordings were performed in a primary astrocyte culture from rat brain and in a human glioblastoma cell line, 138 MG. The technique proved insufficient to verify the heterogeneous composition of the primary astrocyte culture, since this study shows most cells present in the culture to have similar resting membrane potential, membrane impedance, membrane potential/impedance relationship and K+-sensitivity. With the exception of macrophages, identified by their response to externally applied yeast particles, the results do not allow the identification of different cells that are known to be present. The membrane potential of the primary astrocyte was -68 +/- 14 mV, and the membrane potential of the 138 MG cells -37 +/- 15 mV. The membrane potential of cells in the primary culture have a K+-sensitivity resembling that of astrocytes in situ, whereas the K+-sensitivity of 138 MG more resemble that of a dedifferentiated cell. A reduction of 0.95 mm Ca2+ to o mM depolarizes the astrocyte with 9.6 mV and hyperpolarizes the glioma cell 2.6 mV.

Animals↗
PubMed1986

Effects of local administration of GH and IGF-1 on longitudinal bone growth in rats.

The effect of local administration of growth hormone (GH) and insulinlike growth factor 1 (IGF-1) on longitudinal bone growth was studied in the proximal tibia of hypophysectomized rats, by using the tetracycline method. Human GH (hGH) stimulated local bone growth when administered into the epiphysial growth plate, into the epiphysis through an implanted cannula, or into the knee joint intraarticularly. In contrast, hGH administration into the metaphysis did not cause such a stimulation. The effect of hGH was dose dependent, and the lowest daily dose of hGH that caused a stimulation was 50 ng. hGH produced by cloned bacteria was as effective as pituitary-derived hGH, excluding the possibility of a pituitary growth factor being the active compound. GH from other mammalian species (rat GH, ovine GH, and bacterially produced bovine GH) also stimulated local bone growth. Ovine prolactin (oPRL) stimulated local bone growth but the threshold dose of oPRL was approximately 100 times higher than that of hGH, suggesting that contamination of this preparation by GH may account for the stimulation. Reduced carboxymethylated human GH, that has a greatly reduced anabolic activity, did not stimulate local bone growth. Local administration of 5 micrograms of bacterially produced human IGF-1 per day produced a small but significant effect on unilateral bone growth. Simultaneous administration of hGH had no additive effect with, nor did it potentiate, the stimulatory effect of IGF-1. The present study confirms and extends earlier investigations, showing that local injection of GH at the site of the epiphysial growth plate stimulates unilateral bone growth. The study also shows that local administration of IGF-1 stimulates longitudinal bone growth.

Animals↗
PubMed1986

Growth hormone potentiates colony formation of epiphyseal chondrocytes in suspension culture.

The effect of human GH (hGH) on colony formation of rat epiphyseal plate chondrocytes was studied in suspension culture. Chondrocytes were isolated enzymatically from epiphyseal plates of the proximal tibia of 28-day-old normal male rats, and were cultured in a suspension stabilized with 0.5% agarose. After approximately 7 days of culture in the presence of 10% newborn calf serum (NCS), chondrocyte colonies developed consisting of varying numbers of cells in matrix. No colonies developed in the absence of NCS, and the number of formed colonies was proportional to the concentration of NCS (5-20%) in the medium. hGH potentiated the formation of large size colonies (diameter greater than 90 microns) after a culture period of 10 or 14 days. The lowest effective concentration of hGH was 10 ng/ml, while 40 ng/ml hGH gave a maximal stimulatory effect (40-50%). Higher concentrations of hGH (80 and 160 ng/ml) showed reduced potentiation of colony formation. The stimulatory effect of hGH was expressed at 10-15% of NCS at 14 days of culture. There was a linear relation between the number of seeded cells and the number of colonies formed, both in the absence and presence of hGH. These results show that GH potentiates colony formation in chondrocytes of the epiphyseal growth plate, providing further support for the contention that GH exert a direct stimulatory effect on epiphyseal cartilage and thus stimulates longitudinal bone growth directly. The finding that GH preferentially potentiated the formation of large size colonies suggests that GH promoted the differentiation of early proliferative chondrocytes or stem cell chondrocytes with an inherent high capacity to proliferate.

Animals↗
PubMed1986

Magnesium deficiency in IDDM related to level of glycosylated hemoglobin.

Magnesium and potassium were analyzed in plasma, erythrocytes, and urine collected during 24 h and in muscle biopsies from 25 subjects with insulin-dependent, type I diabetes mellitus (IDDM). Magnesium was also measured in mononuclear cells. The results were compared with those of 28 healthy controls, and were also correlated with the degree of diabetic control as estimated by analysis of the level of glycosylated hemoglobin (HbA1c). Subjects with IDDM had significantly lower muscle (P less than 0.01) and plasma (P less than 0.001) concentrations of magnesium compared with those of healthy controls. The HbA1c levels correlated significantly with the concentrations of magnesium in muscle (r = -0.62, P less than 0.001), plasma (r = -0.62, P less than 0.001), and mononuclear cells (r = -0.47, P less than 0.05). The results indicate that some patients with IDDM have lowered contents of magnesium in striated muscular and/or plasma, and that those parameters are dependent on the degree of diabetic control.

Adult↗
PubMed1985

Hepatic retinol metabolism. Distribution of retinoids, enzymes, and binding proteins in isolated rat liver cells.

The main retinoids and some binding proteins and enzymes involved in retinol metabolism have been quantified in different types of rat liver cells. Hepatic perisinusoidal stellate cells contained 28-34 nmol of retinoids/10(6) cells, and parenchymal liver cells contained 0.5-0.8 nmol of retinoids/10(6) cells, suggesting that as much as 80% of more of total liver retinoids might be stored in stellate cells with the rest stored in parenchymal cells. Isolated endothelial cells and Kupffer cells contained very low levels of retinoids. More than 98% of the retinoids recovered in stellate cells were retinyl esters. Isolated parenchymal and stellate cell preparations both contained considerable retinyl palmitate hydrolase and acyl-CoA:retinol acyltransferase activities. Parenchymal cells accounted for about 75-80% of the total hepatic content of these two enzyme activities, with the rest located in stellate cells. On a cell protein basis, the concentrations of both of these activities were much greater in stellate cells than in parenchymal cells. In contrast, cholesteryl oleate and triolein hydrolase activities were fairly evenly distributed in all types of liver cells. Large amounts of cellular retinol binding proteins were also found in parenchymal and stellate cells. Although parenchymal cells accounted for more than 90% of hepatic cellular retinol binding protein, the concentration of the protein in stellate cells (per unit protein) was 22 X greater than that in parenchymal cells. Stellate cells were also enriched in cellular retinoic acid binding protein. Thus, both parenchymal and stellate cells contain substantial amounts of retinoids and of the enzymes and intracellular binding proteins involved in retinol metabolism. Stellate cells are particularly enriched in these several components.

Acyltransferases↗
PubMed1985

Cell density dependent uptake of LDL in cultured rat hepatocytes.

An inverse relationship between low-density lipoprotein uptake and cell density was observed in rat hepatocyte monolayers incubated with lipoprotein-deficient serum. This was also true for cell association, binding and degradation of low-density lipoproteins. Compactin stimulated cell association and degradation of low-density lipoproteins both at low and high concentrations. Insulin, on the other hand, had no consistent effect on low-density lipoprotein cell association or degradation.

Animals↗
PubMed1985

Measurements of magnesium in mononuclear cells.

In this study analysis of magnesium in mononuclear cells was compared to that in muscle in patients and healthy controls. Mononuclear cell concentrations of magnesium expressed as nmol/mg cell protein correlated significantly with muscle biopsy concentrations of magnesium (r = 0,68; p less than 0,001). Hence, we suggest that analyzing of magnesium in mononuclear cells could be an easy and convenient way to estimate tissue magnesium.

Adult↗
PubMed1985

Testicular germ cell tumors after clomiphene therapy for subfertility.

The stimulatory effect of low doses of clomiphene citrate on the human male gonad is accepted widely. We used 25 mg. clomiphene daily for 3 weeks, with 1 week of rest, for 6 to 12 months in 650 oligospermic men without increased serum levels of follicle-stimulating hormone (less than 20 IU/l.). Unilateral testicular neoplasm developed in 2 subjects. Although a definite cause-and-effect relationship between treatment and tumor development cannot be assigned the possible risk of tumor development in men undergoing long-term clomiphene treatment is suggested. Since clomiphene administration or gonadotropin treatment might enhance tumor development in men, patients at risk undergoing such therapy should be examined frequently and when a testicle enlarges a malignant tumor must be ruled out.

Adult↗
PubMed1985

Glycerol metabolism and osmoregulation in the salt-tolerant yeast Debaryomyces hansenii.

A glycerol-nonutilizing mutant of the salt-tolerant yeast Debaryomyces hansenii was isolated. When subjected to salt stress the mutant produced glycerol, and the internal level of glycerol increased linearly in proportion to increases of external salinity as in the wild-type strain. However, at increased salinity the mutant showed a more pronounced decrease of growth rate and growth yield and lost more glycerol to the surrounding medium than did the wild type. Uptake experiments showed glycerol to be accumulated against a strong concentration gradient, and both strains displayed similar kinetic parameters for the uptake of glycerol. An examination of enzyme activities of the glycerol metabolism revealed that the apparent Km of the sn-glycerol 3-phosphate dehydrogenase (EC 1.1.99.5) was increased 330-fold for sn-glycerol 3-phosphate in the mutant. Based on the findings, a scheme for the pathways of glycerol metabolism is suggested.

Glycerol↗
PubMed1985

Efficient hepatic uptake of chylomicron remnant cholesterol in rats with a portacaval anastomosis.

Portacaval-shunted and sham-operated male rats, fed ad libitum and of similar weight, were studied 2-3 weeks after surgery. At this time serum cholesterol levels did not differ significantly between the two groups, whereas serum triacylglycerols and phospholipids were lower in the shunted group. These animals also showed an increased serum bile acid level and an increased serum estradiol to testosterone ratio. The metabolism of native chyle labeled with [3H]cholesterol and [14C]linoleic acid or of preformed chylomicron remnants with the same labeling was studied in the groups of rats. Ten minutes after intravenous injection of chylomicron remnants 10.6 +/- 0.5% (means +/- SEM, n = 8) of the injected [3H]cholesterol and 7.6 +/- 0.4% of the [14C]linoleic acid were found per 1 g liver in the portacaval-shunted rats; the corresponding figures in the sham-operated group (n = 8) were 6.4 +/- 0.4 and 4.9 +/- 0.3, respectively (p less than 0.001 for both 3H and 14C). Thus, despite a greater than 40% reduction of liver weight induced by the shunting procedure, the total liver uptake of chylomicron remnants was not significantly decreased. The uptake of chylomicron lipids per unit liver weight was normal in the atrophic livers of portacaval-shunted rats also when very large loads of chyle were administered.

Animals↗
PubMed1984

Metabolism of chylomicron phosphatidylethanolamine in the rat.

10 min after intravenous injection of 32P-labelled chylomicrons 69% of the [32P]phosphatidylethanolamine, but only 34% of the [32P]phosphatidylcholine, was cleared from plasma. Over this time period the plasma phosphatidylethanolamine concentration that was increased after the chylomicron injection returned to normal, indicating that the rapid clearance of [32P]phosphatidylethanolamine was primarily due to metabolism and not due to exchange with tissue phospholipids. Also after chylomicron [32P]phospholipids had been transferred to high-density lipoproteins in vitro a greater fraction of [32P]phosphatidylethanolamine than of [32P]phosphatidylcholine was eliminated both in the intact rat and in the perfused rat liver. In the latter system the uptake of [32P]phosphatidylethanolamine was reduced by preperfusion with heparin to remove heparin-releasable hepatic lipase. Experiments with hepatocytes and non-parenchymal liver cells, which both contain only minor amounts of surface-bound hepatic lipase, did not demonstrate any rapid uptake of [32P]phosphatidylethanolamine by exchange with cellular phospholipids. This study shows that there is a mechanism for rapid clearance of chylomicron phosphatidylethanolamine, which maintains a low plasma phosphatidylethanolamine level (30-40 micrograms/ml) despite a significant transport of phosphatidylethanolamine with the intestinal lipoproteins. A major part of the rapid phosphatidylethanolamine metabolism occurs in the liver, where the activity of the hepatic lipase is likely to be of crucial importance.

Animals↗
PubMed1984

Anti-IgE-and ConA-induced histamine release from human basophilic leukocytes: the existence of differences in relative responses within individuals.

Histamine release was induced from human blood leukocytes with Concanavalin A (ConA) and two different preparations of anti-IgE. A dose-response curve was constructed for each cell population and secretagogue. No qualitative difference in response pattern was observed with the two anti-IgEs; however, the relative release-inducing efficacy of ConA and anti-IgE seemed to vary with the individual providing the cells. These findings indicate that release induced by ConA is not completely equivalent to that induced by anti-IgE.

Antibodies, Anti-Idiotypic↗