Showing papers in "Scandinavian Journal of Clinical & Laboratory Investigation in 1975"
TL;DR: In this article, a percutaneous needle biopsy of skeletal muscle in Physiological and Clinical Research is described, and the authors present a detailed discussion of the procedure and the results.
Abstract: (1975). Percutaneous Needle Biopsy of Skeletal Muscle in Physiological and Clinical Research. Scandinavian Journal of Clinical and Laboratory Investigation: Vol. 35, No. 7, pp. 609-616.
944 citations
TL;DR: The results show that the method based on two-dimensional scanning photon absorptiometry is eminently suitable for rapid, easy, and atraumatic measurement of local bone calcium in vivo.
Abstract: A method for estimating total bone calcium is reported. The method is based on two-dimensional scanning photon absorptiometry on the distal part of the forearm. The following factors are investigated: precision of measurements on standards and human subjects; linearity; the effect of varying bone orientation; amount of fat and soft tissue; and the relation between weight and content of calcium and phosphate. The results show that the method is eminently suitable for rapid, easy, and atraumatic measurement of local bone calcium in vivo.
153 citations
TL;DR: The results strongly suggest that abnormalglomerular filter properties are present in patients with relatively short duration of diabetes - that is, in patients who are known to have thickened glomerular basement membrane.
Abstract: Urinary albumin excretion during exercise was measured with a radioimmunological method in a group of 13 young male diabetic patients and in a comparable control group. The duration of diabetes was 2–18 years; they had no proteinuria (Albustix®) and no other signs of renal disease. There was no difference in the basal albumin excretion. In the diabetics the average albumin excretion was doubled during exercise at 600 kpm/min for 20 min, from 9.1 μg/min to 18.7 μg/min (P<0.005). No significant change was seen in the controls. These results strongly suggest that abnormal glomerular filter properties are present in patients with relatively short duration of diabetes that is, in patients who are known to have thickened glomerular basement membrane. The exercise provocation test may be useful in other fields of renal pathophysiology.
135 citations
TL;DR: Free triiodothyronine (T3) in serum has been measured directly in dialysates of serum, using a wick chromatographic radioimmunoassay, and adequate sensitivity was attained by the use of [1251]T3 with very high specific activity.
Abstract: Free triiodothyronine (T3) in serum has been measured directly in dialysates of serum, using a wick chromatographic radioimmunoassay. Adequate sensitivity was attained by the use of [1251]T3 with very high specific activity (2,000 to 3,000 muCi/mug). Sera were dialysed against a Krebs-Ringer bicarbonate buffer modified so as to be similar to plasma water. Dialysis took place under carefully controlled circumstances. The influence on the equilibrium of total to free T3 of temperature, serum dilution, and dialysis time was studied. By the present method, free T3 in serum from groups of subjects including 20 men, 10 women taking oral contraceptives, and 20 women with normal menstrual cycles were identical, averaging 5.2 pg/ml. A chromatographic radioimmunoassay of total T3 using high specific activity [1251]T3 and very small test samples is also described.
120 citations
TL;DR: These experiments show that the LCAT reaction can alter the apolipoprotein content and physical properties as well as the lipid content of the patient's lipoproteins.
Abstract: To study the effect of lecithin: cholesterol acyltransferase (LCAT) on the plasma lipoproteins of patients with familial LCAT deficiency, whole plasma or the lipoprotein fraction of d < 1.006 g/ml (VLDL) was incubated in the presence of LCAT and subsequently examined by chemical, physical, and immunological techniques. The following occurred upon incubating either hyperlipemia or nonlipemic plasma: The concentrations of polar lipids decreased, particularly in the large molecular weight lipoprotein subfraction of d 1.019-1.063 g/ml (LDL2) and in the lipoprotein fraction of d 1.063-1.25 g/ml (HDL). The concentration of cholesteryl ester (CE) increased, particularly in the VLDL and in the lipoprotein fractions of d 1.006-1.019 g/ml (LDL1) and LDL2. The concentration of arginine-rich apolipoprotein decreased in the HDL and increased in the VLDL and LDLi. The concentrations of the C-apoliproteins appeared to change in the opposite direction. The concentration of apolipoprotein B in the LDL increased concomitan...
105 citations
Journal Article•
101 citations
TL;DR: Occlusion of the circulation to the quadriceps muscle for 20 min resulted in decreases in the muscle ATP and phosphorylcreatine contents and increases in ADP and AMP, suggesting that the local intramuscular oxygen store was sufficiently depleted at this time as to be limiting to normal mitochondrial function.
Abstract: Occlusion of the circulation to the quadriceps muscle for 20 min resulted in decreases in the muscle ATP and phosphorylcreatine (PC) contents of 1 and 32 per cent, respectively, and increases in ADP and AMP of 7 and 37 per cent. Decrease in PC was statistically significant after 4 min of occlusion, suggesting that the local intramuscular oxygen store was sufficiently depleted at this time as to be limiting to normal mitochondrial function. Pyruvate and lactate concentrations in muscle and the lactate to pyruvate ratio were significantly increased after 15 min of occlusion but not before. The calculated local oxygen store in the muscle was 2.0 mmol O2 - (kg dry muscle)-1. Local oxygen store depletion after 4 and 10 min of occlusion was estimated to be 40-50 and 90-100 per cent complete. Increasing time of pre-exercise occlusion resulted in decreased isometric endurance capacity. The observed decreases in endurance, however, were far greater than could be accounted for by any parallel decrease in the local muscle energy stores.
95 citations
TL;DR: Blood from full-term newborns and capillary or venous blood from 226 children varying in age from 6 weeks to 16 years was examined for content of retinol-binding protein (RBP), prealbumin, and transferrin, whereas the transferrin values reached constant adult levels as early as 2 years of age.
Abstract: Umbilical-cord blood from 50 full-term newborns and capillary or venous blood from 226 children varying in age from 6 weeks to 16 years was examined for content of retinol-binding protein (RBP), prealbumin, and transferrin. The mean levels of the three proteins in the newborns were 21 μg/ml, 128 μg/ml, and 1.65 mg/ml, respectively. The corresponding maternal levels were 39 μg/ml, 231 μg/ml, and 3.2 mg/ml. Paired serum values of mothers and newborns showed a correlation for both RBP and prealbumin but not for transferrin. The low levels of RBP at birth (about 50 per cent of that of nonpregnant women) increased rapidly over the first 6 months to a maximum of 31 μg/ml but declined thereafter to a mean level of about 26 μg/ml, which was maintained until the age of puberty, when adult values were gradually attained. In serum, the prealbumin levels showed a similar development, whereas the transferrin values reached constant adult levels as early as 2 years of age.
95 citations
TL;DR: It is concluded that BMC measurements of the distal part of the forearm give an estimate of total body calcium.
Abstract: The representativity of forearm in bone mineral content (BMC) measurements for estimation of total body calcium is investigated in this article. It is shown that there is a very high correlation between weight and calcium content of examined bone pieces, that there is a high correlation between weight of individual bones and BMC values, that the BMC values from various parts of the skeleton are reasonably well correlated, that the weight of individual bones is highly correlated to the weight of total skeleton, and that there is a reasonably high correlation (r=0.85) between BMC measurements in the distal part of the forearm and total weight of the skeleton. It is concluded that BMC measurements of the distal part of the forearm give an estimate of total body calcium.
93 citations
TL;DR: The general muscle inactivity per se, secondary to the neurological disorder, may lead to a reduced work capacity and the increased heart rate and blood lactate level seem to be correlated to the relative exercise level of each leg.
Abstract: In recent muscle metabolic studies, patients with moderate upper motor neuron lesions showed marked difficulty in performing an equal submaximal work load (bilaterally) in two-legged exercise. For a better evaluation of these patients, studies were performed on each leg separately. Six patients with Parkinson's disease and six with moderate hemiparesis were studied. During one-legged submaximal and maximal exercise, heart rate, oxygen uptake, and blood lactate were determined. Maximal voluntary contraction in knee and ankle flexion and extension for each leg was measured. Succinate dehydrogenase (SDH) activity in the thigh muscles was determined. During submaximal exercise, oxygen uptake, heart rate, and blood lactate increased more in the paretic leg of hemiparetic patients and in the more affected leg of the Parkinson patients. In hemiparetic patients maximal voluntary contraction of flexors and extensors of the knee was significantly reduced in the paretic leg but was reduced even in the nonparetic kne...
63 citations
TL;DR: The time course of acute effects on lipoprotein lipase activity (LLA) in adipose tissue, plasma glycerol, triglyceride, insulin, and blood glucose levels was followed and no significant effect on any of the parameters studied was observed.
Abstract: Glucose or corn oil was given perorally to fasting, young healthy volunteers, and the time course of acute effects on lipoprotein lipase activity (LLA) in adipose tissue, plasma glycerol, triglyceride, insulin, and blood glucose levels was followed. After glucose intake, adipose tissue LLA increased rapidly, reaching a maximum of 80 per cent above initial level after 2 h. Plasma glycerol, reflecting the rate of lipolysis of depot lipids, decreased rapidly, temporally well correlated to the LLA changes. After corn oil intake no significant effect on any of the parameters studied was observed except for an increase in the plasma triglyceride level caused by the influx of dietary lipid.
TL;DR: It is concluded that the concentrations of the large very low and low sensity lipoproteins, the intermediate-sized low density lipoproteinins, and the small high density lipiproteins are related to the absorption and subsequent transport of long chain dietary fatty acids.
Abstract: To study the metabolism of the abnormal plasma lipoproteins in familial lecithin:cholesterol acyltransferase deficiency we performed five dietary experiments designed to perturb their distribution and composition. Four patients with the disease were given successive diets that differed in triglyceride, carbohydrate, or cholesterol content, and after each dietary period the lipoproteins were analyzed by combinations of preparative and analytical ultracentrifuga-tion, gel filtration, chromatography, and disc gel electrophoresis. Lowering the intake of long chain, dietary trigylceride descreased the concentrations of the large very low density lipoproteins, the large and intermediate low density lipoproteins, and the small high density lipoproteins by as much as 79 %, but either increased or did not change the concentrations of the small very low and low density lipoproteins. Re-adding long chain triglyceride to the diet generally reversed these effects, but increasing the intake of carbohydrate did not. Fur...
TL;DR: The technique detects amylase fractions with activities below 10 U/l and some characteristic changes in such diseases as acute and chronic pancreatitis, cystic fibrosis of the pancreas, macroamylasemia and inherited variants as well as after maxillofacial surgery are mentioned.
Abstract: Skude, G. Electrophoretic Separation, Detection, and Variation of Amylase Isoenzymes. Scand. 1. clin. Lab. Invest. 35, 41–47, 1975.An electrophoretic technique for demonstrating amylase isoenzymes is described. After separation in an agarose gel containing a linear polyacryl-amide polymer to reduce electroendosmotic flow, the amylase fractions are visualized by incubation with a commercially available dye-starch polymer (PhadebasB Amylase Test). The technique detects amylase fractions with activities below 10 U/l. Some characteristic changes in such diseases as acute and chronic pancreatitis, cystic fibrosis of the pancreas, macroamylasemia and inherited variants as well as after maxillofacial surgery are mentioned.
TL;DR: Prealbumin, retinol-binding protein, albumin, alpha-lipoprotein and Normotest (NT) were usually highly intercorrelated and separated best among groups with different types of functional impairment.
Abstract: In 9 groups of liver diseases, 11 serum protein parameters were studied. Prealbumin, retinol-binding protein, albumin, a-lipoprotein and Normotest® (NT) were usually highly intercorrelated and separated best among groups with different types of functional impairment. Haptoglobin, C3 and total iron-binding capacity were probably also sometimes reduced by restricted protein synthesis but appeared to be more easily affected by other factors, α1-antitrypsin was often increased in different liver diseases, but a pattern compatible with the ‘acute-phase reaction’ was regularly present only in hepatic tumors. Bile retention was often accompanied by relatively high levels of ceruloplasmin, C3, and α-lipoprotein and by high NT values.
TL;DR: Groups of patients classified mainly on the basis of liver biopsy findings showed functional differences which permitted a consistent reclassification by discriminant functions using laboratory results, dependent on the subsets of liver diseases studied.
Abstract: Patients with different liver diseases were studied by discriminant analysis. Groups of patients classified mainly on the basis of liver biopsy findings showed functional differences which permitted a consistent reclassification by discriminant functions using laboratory results. Optimal combinations of laboratory tests for the separation of liver diseases were defined. Different combinations were found, dependent on the subsets of liver diseases studied.
TL;DR: The 24-h excretion of the proteins showed a very uneven distribution and seven of 10 proteins were excreted in significantly lower quantities in children than in adults.
Abstract: In 239 apparently healthy subjects the 24-h urinary excretion of albumin, transferrin, haptoglobin, IgM, IgG, IgA, immunoglobulin-free lambda and kappa light chains, lysozyme, and beta-2-microglobulin was studied by means of an automated immunoprecipitin reaction. The 24-h excretion of the proteins showed a very uneven distribution. Albumin was excreted in the largest quantities, 1.6–34.2 mg/24 h (0.95 range), and beta-2-microglobulin in the smallest quantities, 0–0.14 mg/24 h (0.95 range). Seven of 10 proteins were excreted in significantly lower quantities in children than in adults.
TL;DR: A radioimmunoassay for quantitation of beta2-microglobulin in serum and urine was described in this paper, where polyethylene glycol 6000 was used to precipitate the antigen-antibody complex.
Abstract: A radioimmunoassay for quantitation of beta2-microglobulin in serum and urine is described. Polyethylene glycol 6000 was used to precipitate the antigen-antibody complex. The assay can be performed within 5 hr. In healthy human subjects (mean age, 30.6 years and 42.0 years for serum and urine determinations, respectively) the mean concentration of beta2-microglobulin in serum was 125 nmol/l (range, 49-190 nmol/l). In men the mean 24-hr urinary excretion was 12.9 nmol (range, 8.6-19.2 nmol), and in women it was 5.5 nmol (range, 2.9-8.7 nmol). The assay range was 0.23-19.40 nmol/l, and the detection limit was 0.042 nmol/l, using a prolonged incubation time. The coefficient of variation based on 20 determinations in serum dilutions with a concentration of beta2-microglobulin of 8.14 and 1.92 nmol/l was 8.1 per cent and 9.0 per cent, respectively.
TL;DR: It is concluded that the BMC measurement is excellently suited for determining the effect of treatment on oste Openia in a group of patients but rather unsuitable for diagnosis of osteopenia in the individual patients.
Abstract: Bone mineral content (BMC) was measured in 127 normal subjects, 54 men and 73 women, aged 21–70 years. BMC was a function of age and sex; it was therefore found relevant to give normal values in 10-year age groups for each sex. BMC was furthermore related to height, weight, surface area, and muscular strength, but the biological scatter was not reduced by correction for surface area. The normal range is expressed in arbitrary units, mmol calcium/m, and calculated total body calcium in grams. Since the latter expression, after determination of the necessary proportion constants, is independent of apparatus construction and location of measurement, and is dependent on the selection of the reference population, it is recommended that the result be expressed in these grams. It is furthermore concluded that the BMC measurement is excellently suited for determining the effect of treatment on osteopenia in a group of patients but rather unsuitable for diagnosis of osteopenia in the individual patients, whereas t...
TL;DR: Using heat effect values determined for the different cell fractions, values could be calculated for whole blood samples which were in full agreement with the values obtained by direct measurements of whole blood.
Abstract: Bandmann, U., Monti M. & Wadso, I. Microcalorimetric Measurements of Heat Production in Whole Blood and Blood Cells of Normal Persons. Scand. J. clin. Lab. Inivest. 35, 121–127, 1975.Microcalorimetric measurements have been made of the heat production in whole blood and its major cell fractions. All measurements were made with samples from normal subjects. The average heat effect value found (±S.D.) for whole blood was 62 ± 7 mW/I. The value obtained for erythrocytes was 82 ± 6 mW per liter of packed cells suspended in phosphate buffer at pH 7.4. For lymphocytes and for polymorphonuclear leukocytes heat effect values were 4.6 ± 1.8 and 1.2 ± 0.4 pW/cell, respectively, for cells suspended in buffer. For plasma suspensions corresponding values were 2.2 ±1.4 and 3.5 ± 1.0 pW/cell, respectively. For thrombocytes suspended in plasma the heat effect value was 59 ± 8 fW/cell. Heat production in cell-free plasma was close to zero. Using heat effect values determined for the different cell fractions, values could ...
TL;DR: It is concluded that an increased NADH2/NAD ratio is the most important factor for the production of 2-HB.
Abstract: Urine and blood samples from patients with different clinical disorders were examined for 2-hydroxybutyric acid (2-HB) by gas chromatography and mass spectrometry. All patients with combined lactic acidosis and ketoacidosis excreted 2-HB in the urine, in amounts up to 2.3 mmol/mmol creatinine. In blood from these patients, 2-HB was present only in trace amounts. Hard physical exercise resulted in lactic acidosis and accumulation of 2-HB. The lactate to pyruvate ratio in blood and urine was markedly increased in the patients excreting 2-HB but was normal in two patients with lactic acidosis who did not excrete 2-HB. It is concluded that an increased NADH2/NAD ratio is the most important factor for the production of 2-HB.
TL;DR: Reduction of interstitial protein concentration is an important factor in preventing edema formation in hypoproteinemia and reducing net transcapillary oncotic pressure is indicated.
Abstract: Protein concentration and hydrostatic pressure were measured in subcutaneous tissue of rats during development of aminonucleoside nephrosis. Samples of interstitial fluid for protein analysis were collected from subcutaneous tissue by a wick method, and hydrostatic pressure was measured by a modified Scholander technique. When the serum protein concentration was reduced from 6.1 to 4.8 g/100 ml, interstitial fluid protein concentration fell from 3.0 to 1.1 g/100 ml. This corresponds to a reduction of calculated oncotic pressures from 18.0 to 13.0 mm Hg and from 7.8 to 3.0 mm Hg in serum and interstitial fluid, respectively, thus leaving a nearly constant net transcapillary oncotic pressure. When serum protein concentration was further reduced to 3.8 g/100 ml, interstitial fluid protein concentration was reduced to 0.5 g/100 ml, reducing net transcapillary oncotic pressure by 2–3 mm Hg. The average hydrostatic pressure in subcutis was 1.0 mm Hg sub-atmospheric under control conditions and did not change du...
TL;DR: In normal subjects there seems to be a direct relation between very low density lipoprotein and LDL lipid concentration and molar LCAT rate but no relation between HDL cholesterol concentration andLCAT rate.
Abstract: Information concerning variation in the lecithin :cholesterol acyl transfer (LCAT) rate in normal persons is scanty. We have therefore analyzed the LCAT rate and the lipid and lipoprotein concentrations in the plasma of healthy normolipidemic persons 20–60 years of age, 40 men and 40 women, 10 per decade and sex. Interindividual variation in molar LCAT rate was 57–130 μmol 1−1. h−1 (mean ± 2 S. D.) with no sex difference. Intraindi-vidual variation of molar LCAT rate studied in 8 women and 9 men was shown to be greater than expected from methodological error and was not explainable by the small changes in plasma lipid concentration during the observation period. In the women the molar LCAT rate was lower during the preovulatory phase of the menstrual cycle than during the postovulatory phase. There were positive correlations between the molar LCAT rate and most of the lipid parameters in plasma. By partial correlation analysis a positive correlation was shown between LCAT rate and triglyceride concentrati...
TL;DR: The investigation shows that the human fetal lung, quite early in gestation, is capable of responding to the action of glucocorticoids by accumulating phospholipids.
Abstract: Lungs obtained from human fetuses with a gestational age of 17, 19, and 24 weeks were cultured as organ culture for 6 days with or without Cortisol. The total phospholipid content per milligram protein in the explants incubated with Cortisol increased by 56–81 per cent compared with the controls. Lecithin accounted for 62–69 per cent of the phospholipid increment in the cortisol-treated explants, whereas only 44.2 per cent of the total phospholipids in the control incubations consisted of lecithin. Cortisol increased the incorporation of [Me-3H]choline into lecithin by 118-224 per cent. The investigation shows that the human fetal lung, quite early in gestation, is capable of responding to the action of glucocorticoids by accumulating phospholipids.
TL;DR: A radioimmunoassay for determination of free light polypeptide chains from human immunoglobulins in serum and urine is described and the mean concentration offree light chains in serum from 20 normal subjects was 10.6 mg/1 for lambda chains and 13.2 mg/ 1 for kappa chains.
Abstract: A radioimmunoassay for determination of free light polypeptide chains from human immunoglobulins in serum and urine is described. The free light chains were isolated from the regular immunoglobulins by gel filtration on Sephadex G-100 columns. In the radioimmunoassay the free and antibody-bound 125I-labelled light chains were separated on gel filtration through Sephadex G-200 columns. The mean concentration of free light chains in serum from 20 normal subjects was 10.6 mg/1 for lambda chains and 13.2 mg/1 for kappa chains. The 24-hr urinary excretion was 1.1 mg for lambda chains and 3.2 mg for kappa chains.
TL;DR: It is concluded that pulmonary stretch reflexes to a minor extent contribute to RSA, whereas the hypothesis of a central nervous origin does not gain support.
Abstract: The effect of tidal volume (VT) and of the intrathoracic pressure (Poes) on the respiratory sinus arrhythmia (RSA) was studied in healthy subjects. They breathed into a spirometer with a VT of 1, 1.5, and 2 1, at a standardized, slow respiratory rate, 6-min-1 (A). Poes was varied by (B) adding a negative inspiratory pressure (NIP) of 5 cm of water and by (C) intermittent positive pressure ventilation (IPPV) at identical VT and respiratory frequency. In a separate study (D), intermittent negative pressure ventilation (INPV) was induced by applying negative pressure on the thorax. In A, increasing VT provoked an augmented RSA by a more marked tachycardia as well as bradycardia. On increasing the amplitude of Poes in B, RSA was somewhat more marked due to a lower minimum heart rate. When comparing respiratory cycles that had similar Poes but a different VT, the larger VT caused a slight increase in the RSA amplitude due to a more marked deceleration of the heart rate. IPPV almost abolished RSA, whereas INPV did not reduce the arrhythmia. It is concluded that pulmonary stretch reflexes to a minor extent contribute to RSA, whereas the hypothesis of a central nervous origin does not gain support. Cardiovascular reflexes remain the main possible cause of RSA.
TL;DR: Biopsies from vastus lateralis muscle of male patients suffering from chronic ethanol abuse were studied with regard to histochemical reactions of ATPase and NADH-diaphorase and enzymatic activities of triosephosphate dehydrogenase, and cytox; content of ATP, creatine phosphate, and glycogen; and volume fractions of fat, mitochondria, and fibrillar and extrafibrillars space.
Abstract: Biopsies from vastus lateralis muscle of male patients suffering from chronic ethanol abuse were studied with regard to histochemical reactions of ATP-ase and NADH-diaphorase; enzymatic activities of triosephosphate dehydrogenase (TPD), lactate dehydrogenase (LD), and cytochrome c oxidase (cytox); content of ATP, creatine phosphate, and glycogen; and volume fractions of fat, mitochondria, and fibrillar and extrafibrillar space. The results were compared with those from controls without known abuse of ethanol. The relative numbers of fibers were the same in the two groups, but the size of the fast-twitch-glycolytic (white) fibers was diminished in the alcoholic group. The activities of TPD and LD were diminished in skeletal muscle of the alcoholics. This is most probably caused by the reduced amount of fast-twitch-glycolytic tissue, as there was a good correlation between this amount and the activity of the two enzymes. The activity of cytox was slightly lower in muscle of the alcoholics than in that of th...
TL;DR: A method is described for the determination of metabolites in liver biopsy samples and the extent of adenine nucleotide depletion varied greatly between subjects and appeared related to the degree of increase in plasma urate.
Abstract: A method is described for the determination of metabolites in liver biopsy samples. Normal values of lactate, pyruvate, and adenine nucleotide content of human liver are presented. Infusion of D-fructose, 5.9 mmol. kg−1. h−1, for 70 min resulted in a 22.5 per cent decrease of the adenine nucleotide pool (mainly by ATP depletion), increased content of fructose 1-phosphate, lactate, and pyruvate. The extent of adenine nucleotide depletion varied greatly between subjects and appeared related to the degree of increase in plasma urate. Infusions of glucose at the same rate did not affect the hepatic content of adenine nucleotides.
TL;DR: Plasma from a patient with familial lecithin:cholesterol acyltransferase deficiency did not esterify any of the sterols, and the esterification of desmosterol and beta-sitosterol was considerably slower in normal plasma in which in vitro cholesterol esterified previously had taken place.
Abstract: Desmosterol and beta-sitosterol were esterified when incubated with normal human plasma. The initial rate of demosterol esterification was 1.7 times faster, and that of beta-sitosterol 0.4 times slower, than the esterification rate of cholesterol. These ratios were found to be almost the same when plasma from different normal individuals was tested. Plasma from a patient with familial lecithin:cholesterol acyltransferase deficiency did not esterify any of the sterols. The esterification of desmosterol and beta-sitosterol was considerably slower in normal plasma in which in vitro cholesterol esterification previously had taken place. The different esterification rates could not be explained by a different affinity of the plasma lipoproteins for the sterols tested. Cholecalciferol added to normal plasma did not become esterified.
TL;DR: Crucial and previously criticized points in a slightly modified version of the Stokke-Norum assay of fractional lecithin:cholesterol acyl transfer (LACT) rate in plasma were studied and this methodology is considered to be suitable for studies of LCAT and cholesterol turnover in different metabolic situations and clinical materials.
Abstract: Crucial and previously criticized points in a slightly modified version of the Stokke-Norum assay of fractional lecithin:cholesterol acyl transfer (LACT) rate in plasma were studied. LCAT activity in the albumin added to the assay medium and negative influence of remaining organic solvent were important sources of error that it was necessary to eliminate. The assumption of equilibration of labeled cholesterol among lipoproteins in vitro was supported experimentally. Addition of isolated chylomicrons had no influence on initial LACT rate. Incubation time was decreased to 20 minutes to obtain a better estimate of initial LCAT rate in normals. Using gas-liquid chromatography to determine unesterified cholesterol concentration, the precision of measurement of molar LCAT rate was 5.2 per cent (coefficient of variation). Molar LCAT rate in healthy males 20-60 years of age was 56-130 mumol-1(-1)-h-1 (mean +/- 2 S.D.) and compared well with reports from other laboratories and in vivo measurements. At present this methodology is considered to be suitable for studies of LCAT and cholesterol turnover in different metabolic situations and clinical materials.
TL;DR: The diagnosis of type III hyperlipoproteinaemia is based on the presence of a very low density lipoprotein (VLDL) that on electrophoresis has beta instead of the usual pre-beta mobility, but on agarose gel their mobility was slightly more rapid than beta, and the possibility of a metabolic relation is discussed.
Abstract: The diagnosis of type III hyperlipoproteinaemia is based on the presence of a very low density lipoprotein (VLDL) that on electrophoresis has /J instead of the usual pre-β mobility. This definition is based on paper electrophoresis. Lipoproteins of type III sera were studied by simultaneous electrophoresis on paper and on agarose gel. On paper the ultracentrifugally isolated VLDL had β mobility, but on agarose gel their mobility was slightly more rapid than β. It is thus important to consider the electrophoretic conditions in the diagnosis of type III. The diagnosis of type III is further complicated by the presence in agarose gel electrophoresis—contrary to paper—of a second, a ‘late pre-β VLDL’ lipoprotein (LPβ) in 20–30 per cent of both normal and hyperlipoproteinaemic sera. Quantitative lipoprotein analysis of 609 consecutive sera showed that when LPyβ was present, both in normo- and hyperlipoproteinaemia, certain significant lipoprotein changes occurred. Thus VLDL had a high cholesterol content and a...