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Biomedical subjects

B Lundberg

Publications and source records attributed to B Lundberg.

At least 55 records · Page 3Linked to original sources
PubMed1986

Evaluation of "HemoCue," a new device for determining hemoglobin.

Hemoglobinometry according to the International Committee of Standardization in Hematology (ICSH) suffers from imprecision related to high sample dilution and from potential errors owing to sample turbidity. We have evaluated a new instrument, "HemoCue," that measures hemoglobin at two wavelengths as azide methemoglobin, without dilution. The HemoCue method is superior to the ICSH method: by correction for turbidity, it avoids false hemoglobin readings that may arise from hyperlipemia or some large M-component of the immunoglobulin M class. We find the equipment suitable for use in outpatient units.

Evaluation Studies as Topic↗
PubMed1985

Accumulation and mobilization of cholesteryl esters in cultured human fibroblasts exposed to free cholesterol-rich phospholipid vesicles.

The uptake of free cholesterol (FC) into cells by surface transfer and its esterification to cholesteryl esters (CE) has been studied with a system of FC-egg phosphatidylcholine (EPC) vesicles and human lung fibroblasts in serum-free growth medium. The influx of FC was dependent on the molar ratio of FC to EPC in the donor vesicles. The FC incorporated by surface transfer was available for esterification in the cells. Incubations with FC/EPC vesicles with a FC/EPC molar ratio of 0.5: 1 gave a small net decrease in cellular CE, while 1:1 vesicles gave a mild increase. When the cells were incubated with 2:1 FC/EPC vesicles an extensive accumulation of CE was demonstrated, which was accentuated if albumin was present in the medium. The CE accumulated in the form of lipid droplets within the cells. The largest of these droplets exhibited positive birefringence with formée crosses, that is typical for liquid crystals of cholesteryl esters. If cells loaded with CE were incubated with vesicles with low FC/EPC ratios a net efflux of CE was noted. The present study demonstrates that the uptake of FC from lipid vesicles by surface transfer can reproduce typical features of foam cells in early atherosclerosis.

Carbon Radioisotopes↗
PubMed1985

Chemical composition and physical state of lipid deposits in atherosclerosis.

The composition, morphology, and physical properties of lipids in atherosclerotic lesions from human aortas were studied in order to elucidate the factors for the accumulation of cholesterol and its esters in the vessel wall. Lesions were classified histologically into 3 groups: fatty streak, fibrous plaque, and advanced plaque. The relative lipid composition of the lesions was plotted on the phase diagram of the 3 major lipids: cholesterol, cholesteryl ester, and phospholipid. Early fatty streaks had compositions within the 2-phase zone with a cholesterol-phospholipid liquid crystalline phase and a cholesteryl ester oily phase. Advanced fatty streaks and fibro-fatty plaques fell within the 3-phase zone with excess free cholesterol. Advanced plaques also had an average lipid composition within the 3-phase zone, but with a larger excess of free cholesterol. From the lipid-chemical point of view there is a continuous progression from early fatty streaks through advanced fatty streaks and fibro-fatty plaques to advanced plaques. In fatty streaks the cholesteryl esters accumulate in the form of isotropic and anisotropic droplets. The latter are in the smectic liquid crystalline state with the molecules arranged in layers and have surfaces that are spherical and smooth. Fibrous and advanced plaques showed beside droplets also amorphous lipids and cholesterol monohydrate crystals. Some of the amorphous lipids were solid up to about 45 degrees C and exhibited a smectic phase at cooling, indicating cholesteryl esters as the major component. The transition temperatures of high-melting cholesteryl esters, e.g. palmitate, are depressed by low-melting ones. Most of the triglycerides are present in the cholesteryl ester droplets and abolish the cholesteric liquid crystalline phase.

Adult↗
PubMed1984

Intracellular transport and esterification of exchangeable cholesterol in cultured human lung fibroblasts.

We have studied the intracellular fate of exchangeable cholesterol in a model system with lipid vesicles (cholesterol/phospholipid mole ratio 1:1) and cultured human lung fibroblasts. Exchangeable [3H]cholesterol in lipid vesicles was readily incorporated into cellular plasma membranes and transported to intracellular esterification sites. The formation of [3H]cholesteryl esters was not affected by cytoskeleton-disrupting drugs. A reduction of cellular pinocytosis by 75% did not reduce the formation of tracer-labelled esters, suggesting that membrane flow due to the energy-dependent pinocytosis is no major contributor to the intracellular transport of molecular cholesterol between plasma membranes and esterification sites. The formation of [3H]cholesteryl esters was not significantly affected by energy poisons (NaF and KCN) but was inhibited (to 50%) by chloroquine at 50 microM. This may indicate that membrane-derived cholesterol passes through the lysosomal compartment on its way to intracellular esterification sites.

Cells, Cultured↗
PubMed1984

Purification of lysosomal cholesteryl ester hydrolase from rat liver by preparative isoelectric focusing.

Ion-exchange chromatography and preparative isoelectric focusing (PIEF) were compared to produce a stable rat liver lysosomal cholesteryl ester hydrolase of high specific activity. The PIEF purification method proved to be more rapid and easier to perform. PIEF purification involved the following steps: i) osmotic shock of the lysosome fraction, ii) (NH4)2 SO4 precipitation (10-70%, w/v), iii) Sepharose CL-6B gel filtration, and iv) PIEF. The enzyme was purified 60-120-fold with a yield of 2-4%. The activity of the purified enzyme was best restored by stabilizing with a 0.5% (w/v) albumin solution. The purified enzyme produced one major band on SDS-polyacrylamide gel electrophoresis having a MW of 58,500 daltons. Gel filtration showed a MW of 58,000 daltons. The optimum pH of the enzyme was 4.5, and the isoelectric point was 6.0-6.2. The specific activity of hydrolysis of cholesteryl oleate and triolein increased by similar rates during purification.

Animals↗
PubMed1984

Incorporation of cholesterol into serum high density lipoprotein apoprotein and recombinants.

The uptake of cholesterol (CHL) by serum high density lipoprotein (HDL) delipidated apoproteins and phospholipid-apoprotein recombinants has been studied with two methods; by incubation with Celite-dispersed cholesterol or with cholesterol crystals. The apoproteins bind very small amounts of cholesterol with a maximum of about 6 micrograms/mg apoprotein. Recombinants with dimyristoyl phosphatidylcholine (DMPC) or egg phosphatidylcholine (EPC) as phospholipid component gave similar values for cholesterol uptake. The initial rate for uptake from Celite-cholesterol by recombinants was high (0.1 mol cholesterol/mol phospholipid/h) and somewhat higher than that for phospholipid vesicles. The maximal uptake was by gel filtration shown to depend on the size of the complexes with values about 0.95 mol cholesterol per phospholipid for vesicular complexes, 0.75 for discoidal complexes and between 0.5 and 0.2 for small 'protein-rich' complexes. During the incubation of recombinants with cholesterol there was considerable decomposition of discoidal complexes and formation of larger ones. The results show that phospholipid-apoprotein complexes are efficient acceptors for cholesterol but also that about 25% of the phospholipid in the discoidal complexes is excluded from interaction with cholesterol by interaction with apoprotein.

Apolipoproteins↗
PubMed1984

Separation of plasma high-density lipoprotein subclasses by a combined precipitation method using polyethylene glycol 6000 and dextran sulphate.

A fast and cheap precipitation method for the separation of HDL subclasses been evaluated. It starts with precipitation of apo-B containing lipoproteins with PEG-6000 after which HDL2 is precipitated with dextran sulphate-Mg2+. A concentration of 0.72 g/l dextran sulphate was found to be suitable for the separation of HDL subclasses. HDL subclasses obtained by precipitation gave proper density profiles at density gradient centrifugations. The correlations between results obtained by this method and by sequential and density gradient centrifugation are good, r = 0.99 and 0.72, respectively.

Adult↗
PubMed1984

Information and regime at low back pain.

In a consecutive series of 56 District Health patients with low back pain, 24 had special training and instructions in a Back School, while the 32 in a control group--even if seen regularly, did not get the same intense attention. The two groups were found to have the same characteristics. No significant differences could be demonstrated either concerning the initial duration of symptoms and sick leave or the number of recurrences and their duration during the observation year. The interpretation of this lack of positive effect is, that in this comparatively more heterogenous population the actual procedure has less influence. However, there were more patients with periods of sick-leave for different other reasons in the control group. Not surprisingly the treated group of patients were also more satisfied. We therefore conclude, that the initial treatment could be limited to advice about back care, preferably a few days bed-rest, with concrete advice about the back and prescriptions for analgesics when needed.

Absenteeism↗
PubMed1984

Boston thoracic brace in the treatment of idiopathic scoliosis. Initial correction.

The Boston thoracic brace, i.e., a Boston brace with axillary support, was used to treat thoracic scoliosis in 44 patients. The mean initial correction for curves with the apex at T8-T9 was 15.9 degrees +/- 6.1 degrees (54%). This was a great and significant improvement over results obtained with both the Boston brace and the Boston Milwaukee brace. This degree of correction confirms earlier observations that the increased efficiency of the brace outweighs the disadvantages of the axillary component and encourages further efforts in the direction of nonsurgical treatment of the early stages of scoliosis.

Adolescent↗
PubMed1984

Preparation of biologically active analogs of serum low density lipoprotein.

A method for the preparation of stable and water-soluble analogs of low density lipoprotein (LDL) is presented. The experimental protocols start with the preparation of a cholesteryl ester/phospholipid microemulsion by a combined injection-sonication procedure and delipidation of apoprotein B (apoB) with sodium deoxycholate (NaDOC). The association of lipid microemulsion and NaDOC-solubilized apoB is achieved by incubation and sonication of the components above the melting point of the cholesteryl ester. The reconstituted model LDL (m-LDL) proved to be quite homogeneous both with respect to particle size and composition. Negative-stain electron microscopy shows spherical particles with a mean diameter of 21 nm. The mean density of the reconstituted LDL was 1.07 g/ml as determined by sucrose density gradient centrifugation. The reconstituted LDL retained its beta-mobility on agarose gel electrophoresis, and sodium dodecyl sulfate (SDS)-gel electrophoresis showed no degradation of apoB during the reconstitution procedures. Studies of biological activity showed that the m-LDL particles are bound, incorporated, and degraded by human fibroblasts in a way similar to native LDL. The reconstituted m-LDL has potential use for metabolic, physiochemical, and enzymatic studies of lipoproteins.

Apolipoproteins↗
PubMed1983

Transfer of [3H]cholesterol between lipid vesicles and rat arterial smooth muscle cells in vitro.

Unesterified [3H]cholesterol is rapidly transferred between cholesterol-phosphatidylcholine vesicles and rat arterial smooth muscle cells in vitro. Exchange rate is influenced by the vesicle/cell ratio in a saturable way. The maximal transfer of cholesterol, which is 3.76 micrograms per mg cell protein during 4 h, is achieved with a vesicle/cell ratio of 3.4 X 10(7). Bovine serum albumin enhances the exchange by a factor of 4.5 compared to a protein-free system. The activation energy for the process is + 38.5 kJ X mol-1 with vesicles of 1:1 mole ratio of cholesterol to phosphatidylcholine (C/P). A fraction of the incorporated free [3H]cholesterol is esterified within 4 h with donor vesicles of over 1:1 C/P. When cells were incubated with vesicles of low C/P mole ratio (1:2) a fraction of the incorporated free [3H]cholesterol was esterified within 16 h. Our results are compatible with the aqueous diffusion mechanism of cholesterol exchange. Furthermore, we suggest that, in rat smooth muscle cells, the cell membrane cholesterol pool is not metabolically isolated from internal cholesterol pools, at least as judged by the ability of the cells to esterify incorporated free cholesterol.

Animals↗
PubMed1983

Bristow-Latarjet procedure for recurrent anterior dislocation of the shoulder. A 2-5 year follow-up study on the results of 112 cases.

A follow-up study of 111 out of 112 patients operated on for shoulder joint dislocation according to the Bristow-Latarjet procedure during the years 1975 through 1979 in four Swedish hospitals is presented. The average follow-up time was 30 months (range 24-60 months). There were seven cases of significant recurrences (6 per cent). During follow-up, further surgery had been performed on four of these. Another eight patients (7 per cent) had experienced occasional insignificant subluxations. In one case neurolysis of the musculocutaneous nerve was undertaken because of postoperative paresis of elbow flexors. The average limitation of outward rotation as compared with the nonoperated side was 19 degrees in adduction and 21 degrees in abduction. There was a measurable difference in strength between the operated and nonoperated shoulders. The results were considered excellent or good by 101 of the patients (90 per cent), fair by eight and bad by three. Of 12 cases with failed surgery before the Bristow-Latarjet procedure 10 regarded the result as good or excellent.

Adolescent↗
PubMed1983

Effects of cholesterol surface transfer on cholesterol and phosphatidylcholine synthesis in cultured rat arterial smooth muscle cells.

The purpose of this study was to examine the effects of cholesterol surface transfer between lipid vesicles and rat arterial smooth muscle cells on endogenous synthesis of cholesterol and phosphatidylcholine. Lipid vesicles containing cholesterol and egg phosphatidylcholine in different proportions were used as the extracellular lipid source. The rate of cellular cholesterol and phosphatidylcholine synthesis was determined from the [14C]acetate incorporation into these lipid classes. [3H]Cholesterol in lipid vesicles, with a cholesterol/phospholipid (C/P) mole ratio of 1:1, was rapidly transferred into rat smooth muscle cells, with a half-time of about 3.6 hours in the absence of serum proteins. Incubation of cells for 5 hours with vesicles of a high C/P mole ratio (i.e. 1.5:1) at vesicle-cholesterol concentrations above 100 micrograms/ml resulted in a marked reduction of cellular cholesterol synthesis, whereas the rate of phosphatidylcholine synthesis was increased. Cells incubated with lipid vesicles of C/P 1:2 did not show any change in cellular cholesterol or phosphatidylcholine synthesis. Incubation of cells with egg phosphatidylcholine vesicles at concentrations above 300 micrograms/ml, on the other hand, stimulated endogenous synthesis of cholesterol without affecting cellular phosphatidylcholine synthesis. The main conclusion is that cholesterol surface transfer may influence cellular lipid metabolism in the absence of mediating serum lipoproteins in a model system with cultured cells and lipid vesicles.

Acetates↗
PubMed1983

The coracoid transfer for recurrent dislocation of the shoulder. Technical aspects of the Bristow-Latarjet procedure.

One hundred and twelve shoulders with recurrent anterior dislocation were treated with the Bristow-Latarjet procedure and had a two to five-year follow-up after surgery. The incidence of redislocation was 6 per cent, and an additional 7 per cent of the patients reported occasional subluxation. In 106 shoulders, a radiographic study was carried out in order to determine the importance of factors such as healing and position of the transferred coracoid process with regard to the postoperative clinical results. No redislocation or subluxation occurred in the forty patients in whom the transplant showed osseous or fibrous union at the scapula and was located inferior to the equator of the glenoid and less than one centimeter medial to its rim. In shoulders in which either the transplant had migrated more than 1.5 centimeters from that position or was placed one centimeter or more medial to the glenoid rim, the incidence of redislocation or subluxation was significantly increased.

Adolescent↗
PubMed1982

Plasma concentrations of valproate during maintenance therapy in epileptic children.

A total of 20 children with various types of epilepsy were treated with valproate, 11 with monotherapy and 9 with valproate in combination with phenobarbitone, phenytoin, or carbamazepine. Valproate was given either every 8 or 12 h. At least two different dose levels were tried in each patient. The pharmacokinetics of valproate during the interval between doses was determined using a gas chromatographic technique. The clinical effect of the treatment was assessed by interviewing the parents. The plasma concentrations showed considerable fluctuation during the intervals between doses. The mean increase from pre-administration to peak level was 82% when the dose interval was 12 h, and 62% when it was 8 h. The mean plasma half-life of valproate, using a one-compartment model, was 10.9 +/- 1.3 h (mean +/- SD). The plasma half-life of valproate was decreased when the drug was combined with the other anti-epileptics. The calculated area under the concentration versus time curve was linearly related to dose, both in a single patient on four dose levels and when different patients were compared. The clinical effect of valproate monotherapy was best in patients with absences, usually good in myoclonus and less favourable in other types of epilepsy. For children with absences, the optimal dose range of valproate was between 20 and 40 mg/kg/24 h. In comparison, the myoclonic types of epilepsy needed a slightly higher dose level, between 30 and 60 mg/kg/24 h. In the latter group a "therapeutic window" seems to exist, since patients below and above the suggested dose levels were not well-controlled. Therapeutic monitoring of valproate does not appear meaningful when the drug is used as monotherapy. However, in combination therapy, determination of the plasma levels of all anti-convulsants used may be helpful. The large fluctuations of valproate during a dose interval must be taken into consideration when the clinical effects are analysed.

Adolescent↗
PubMed1982

Incorporation of cholesterol into serum high and low density lipoproteins.

Excess cholesterol (CHL) was incorporated into serum lipoproteins by incubation with Celite-dispersed CHL or CHL crystals. The initial rates of uptake were 15 and 7 mol CHL/ mol lipoprotein X h-1 for low (LDL) and high (HDL) density lipoprotein, respectively. Saturation values were obtained after 48 h and were 90 and 65 mol CHL/mol LDL, and 42 and 32 mol/mol HDL using CHL on Celite and CHL crystals, respectively. Characterization of the lipoproteins showed a small change in electrophoretic mobility and an increase in molecular masses, especially after incubation with CHL on Celite. Spectroscopic methods showed only minor effects on the protein moieties.

Cholesterol↗