STUDIES IN CONGENITAL GENERALIZED LIPODYSTROPHY

1975 ◽  
Vol 79 (4) ◽  
pp. 720-728 ◽  
Author(s):  
Oddmund Søvik ◽  
Svein Oseid
Keyword(s):  
Plasma Insulin ◽  
Dilution Effect ◽  
Insulin Level ◽  
Tolerance Test ◽  
High Plasma ◽  
Epididymal Adipose Tissue ◽  
List Type ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Congenital Generalized Lipodystrophy

ABSTRACT Suppressible and non-suppressible insulin-like activities (ILA) of plasma from 3 patients with congenital generalized lipodystrophy have been studied, employing isolated fat cells from rat epididymal adipose tissue. In all 3 patients the fasting ILA was markedly increased compared with the normal controls. In one of the patients (I. T.) total ILA rose to about 800 μU per ml during an iv glucose tolerance test. The observed total ILA was in all cases (controls included) equal to or slightly higher than the previously determined immunoreactive plasma insulin (IRI). The exact determination of ILA was, however, hampered by a dilution effect, which was present even at high plasma dilutions. In 2 of the patients addition of insulin antiserum inhibited plasma ILA by about 50 %. In the third patient (I. T.), who exhibited the highest insulin level, at least 85 % of the activity was suppressed by insulin antibodies. The levels of non-suppressible ILA were higher than in the controls in terms of μU per ml, but lower than in the controls when related to total ILA. These findings strongly support our previous conclusion that the elevated plasma insulin seen in congenital generalized lipodystrophy is mainly due to true pancreatic insulin. Since the effect of plasma insulin on isolated fat cells were freely expressed, i. e. suppressible ILA was equal to or slightly lower than IRI, the presence of a circulating insulin antagonist in this disease may be excluded.

STUDIES IN CONGENITAL GENERALIZED LIPODYSTROPHY

1973 ◽  
Vol 72 (3) ◽  
pp. 495-505 ◽  
Author(s):  
Oddmund Søvik ◽  
Svein Oseid
Keyword(s):  
Biological Activity ◽  
Insulin Response ◽  
Epididymal Adipose Tissue ◽  
Large Individual ◽  
Immunoreactive Insulin ◽  
List Type ◽  
Glucose Load ◽  
Congenital Generalized Lipodystrophy ◽  
The One

ABSTRACT The biological activity of plasma insulin from 4 cases of congenital generalized lipodystrophy has been studied, using rat diaphragm and epididymal adipose tissue in vivo. The results are compared with previous data on plasma immunoreactive insulin obtained in these patients. 2 of the 4 cases exhibited unusually high biological insulin activities during the fasting state as well as after an intravenous (iv) glucose load. In the fat pad assay activities as high as 10 000 μU insulin per ml were observed. During childhood the biological insulin activities were generally high, although there were large individual variations. However, in the one case studied after the age of puberty, the insulin response to a glucose load was negligible. Taken together, the biological and immunological activities observed strongly suggest the presence of pancreatic insulin in these patients. It appears that the circulating insulin has a fully biological activity. The decreasing insulin activities after cessation of growth are in agreement with the appearance of frank diabetes at this time.

scholarly journals Effect of nutrition on subcellular localization of rat fat-cell lipoprotein lipase

1978 ◽  
Vol 172 (2) ◽  
pp. 239-245 ◽  
Author(s):  
A Vanhove ◽  
C Wolf ◽  
M Breton ◽  
M C Glangeaud
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Plasma Membranes ◽  
Total Activity ◽  
Normal Diet ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell ◽  
Intact Tissue

This study supports the possibility for multiple subcellular forms of lipoprotein lipase. 1. The total activity of lipoprotein lipase per g of intact epididymal adipose tissue from fed rats is much higher than that from starved rats. 2. The isolated fat-cells of fed and of starved rats have lipoprotein lipase of almost the same activity per g of fat-pads. The isolated fat-cells of starved rats have a much higher proportion of total activity per g of the intact tissue than do those of fed rats. 3. Under the conditions of homogenization used, only a small proportion of the total activity per g of intact tissue from fed rats was associated with the fat layer which floated to the top of the homogenate during low-speed centrifugation. The different proportions of the specific enzyme activity found in each subcellular fraction are described. 4. Lipoprotein lipase from plasma membranes and microsomal fractions from starved and fed rats was purified by affinity chromatography. 5. The total activity of microsomal lipoprotein lipase per g of intact adipose tissue is enhanced by a normal diet. 6. In intact epididymal adipose tissue from fed rats, the activity per g of tissue of lipoprotein lipase of plasma membranes is much higher than that in the same fraction from starved rats. By contrast, the activities per g of tissue in plasma membranes obtained from starved or from fed rats by collagenase treatment were similar.

STUDIES IN CONGENITAL GENERALIZED LIPODYSTROPHY

1973 ◽  
Vol 73 (4) ◽  
pp. 731-739 ◽  
Author(s):  
Oddmund Sövik ◽  
Svein Oseid ◽  
Stephanie Öyasæter
Keyword(s):  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Immunoreactive Insulin ◽  
List Type ◽  
Glucose Load ◽  
Crystalline Insulin ◽  
Congenital Generalized Lipodystrophy ◽  
Small Peak ◽  
Two Peaks

ABSTRACT Plasma from 3 subjects with congenital generalized lipodystrophy was filtered on Sephadex G-50, and the fractions obtained were analyzed for immunoreactive insulin (IRI). In one patient (I.T.) plasma was obtained in the course of an iv glucose tolerance test, during which there was a substantial increase of IRI. In the fasting state IRI was recovered as a single peak with an elution volume corresponding to crystalline insulin. Twenty min after the glucose load the insulin immunoreactivity appeared in two peaks, a major peak corresponding to crystalline insulin ("little" insulin) and a small peak corresponding to beef pro-insulin ("big" insulin). The relative amount of "big" insulin remained small during the glucose tolerance test. Twenty min after the glucose load the amount of "big" insulin was 4 per cent, whereas 6 per cent was found after 170 min. In a second patient (L.S.N.) with a substantially, lower IRI-activity "big" insulin was not detected after a glucagon load. Likewise, in a third patient (A.E.) with frank diabetes, studied after the age of puberty, a tolbutamide tolerance test failed to reveal any significant amount of "big" insulin.

scholarly journals Rates of efflux and intracellular concentrations of potassium, sodium and chloride ions in isolated fat-cells from the rat

1969 ◽  
Vol 115 (5) ◽  
pp. 865-871 ◽  
Author(s):  
M. C. Perry ◽  
C. N. Hales
Keyword(s):  
Atomic Absorption Spectrophotometry ◽  
Chloride Ions ◽  
Intracellular Water ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
First Order ◽  
Inulin Space ◽  
Intracellular Concentrations ◽  
Water Space

1. The metabolism of K+, Na+ and Cl− has been investigated in isolated fat-cells prepared from the epididymal adipose tissue of rats. 2. Methods are described for measuring the intracellular water space, the rates of loss of intracellular 42K+, 22Na+ and 36Cl− and the intracellular concentrations of K+, Na+ and Cl− in isolated fat-cells. 3. The intracellular water space, measured as the [3H]water space minus the [carboxylic acid−14C]inulin space, was 3·93±0·38μl./100mg. cell dry wt. 4. The first-order rate constants for radioisotope effluxes from isolated fat-cells were 0·029min.−1 for 42K+, 0·245min.−1 for 22Na+ and 0·158min.−1 for 36Cl−. 5. The intracellular concentrations of K+, Na+ and Cl− were 146m-equiv./l., 18·6±2·9m-equiv./l. and 43±2·4m-equiv./l. respectively. 6. The total intracellular K+ content of isolated fat-cells was determined by atomic-absorption spectrophotometry to confirm the value obtained from the radioisotope-efflux data. 7. The ion effluxes from isolated fat-cells were: K+, 1·5pmoles/cm.2/sec., Na+, 1·6pmoles/cm.2/sec., and Cl−, 2·4pmoles/cm.2/sec. 8. The membrane potential of isolated fat-cells calculated from the Cl− distribution ratio was −28·7mv.

scholarly journals Clearing-factor lipase in adipose tissue. Distinction of different states of the enzyme and the possible role of the fat cell in the maintenance of tissue activity

1969 ◽  
Vol 112 (2) ◽  
pp. 203-209 ◽  
Author(s):  
V. J. Cunningham ◽  
D S Robinson
Keyword(s):  
Adipose Tissue ◽  
Lipase Activity ◽  
Total Activity ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell ◽  
Prolonged Incubation ◽  
Intact Tissue

1. Incubation of intact epididymal adipose tissue from fed rats at 37° in an albumin solution at pH7·4 in vitro results in rapid loss of clearing-factor lipase activity until a low activity, stable to prolonged incubation, is attained. The clearing-factor lipase activity of intact tissue from starved rats, which is initially much less than that of tissue from fed rats, is mainly stable to incubation at 37°. 2. Much of the clearing-factor lipase activity of intact epididymal adipose tissue from fed rats is inactivated by collagenase. The enzyme activity of intact tissue from starved rats is not inactivated by collagenase. 3. The clearing-factor lipase activity of fat cells isolated from the epididymal adipose tissue of fed rats is stable to prolonged incubation at 37°. It represents only a small proportion of the total activity of the intact tissue. In starved rats, the isolated fat cells contain a much higher proportion of the activity of the intact tissue. Their activity is also stable at 37°. 4. Incubation of isolated fat cells in a serum-based medium leads to a progressive rise in clearing-factor lipase activity. Actinomycin increases the extent of this rise in activity. No rise in clearing-factor lipase activity occurs when stromal-vascular cells isolated from epididymal adipose tissue are incubated in the medium. 5. The findings indicate that less than 20% of the activity of intact adipose tissue from fed rats is retained when fat cells are isolated from the tissue by collagenase treatment. The activity that is lost could be that which normally functions in the uptake of triglyceride fatty acids by the tissue.

ON THE SIGNIFICANCE OF SERUM DILUTION AND CORTISOL ANTAGONISM IN THE RAT FAT PAD BIOASSAY OF INSULIN

1968 ◽  
Vol 58 (1) ◽  
pp. 11-26 ◽  
Author(s):  
Ingmar Lundquist
Keyword(s):  
Human Serum ◽  
Species Difference ◽  
Dilution Effect ◽  
Diabetic Rats ◽  
Normal Human Serum ◽  
Epididymal Adipose Tissue ◽  
List Type ◽  
High Concentration ◽  
Undiluted Serum ◽  
Normal Human

ABSTRACT The dilution effect of normal human serum was readily detectable at small dilutions (1:3, 1:4) and was present to about the same extent both in males and females. It was found to be significantly greater in elderly as compared to younger subjects. Adrenalectomized rats had a significantly lower SILA level in undiluted serum than normal rats. Alloxan diabetic rats had a SILA level in undiluted serum, of about one third of the SILA level in normal rats. In contrast to normal human serum, any dilution effect of normal rat serum was detectable only at very high dilutions (1:27). The same pattern was found when serum from adrenalectomized and alloxan diabetic rats were assayed. The dilution effect in human serum is considered to be due mainly to a species difference. The smallest concentration of cortisol which produced a significant suppression of glucose utilization (as measured on the 14CO2 production from Glucose-1-14C) by rat epididymal fat pads in vitro, in the absence of insulin, was of the order of 0.0025 μg per ml (7 × 10−9 m). A linear log dose-response relationship was found between 0.0025 and 0.25 μg per ml and thus was well within the physiological range. Physiological concentrations of cortisol significantly suppressed the effect of submaximal concentrations of insulin on the 14CO2 production from Glucose-1-14C by the epididymal adipose tissue. A maximal insulin concentration abolished this cortisol effect. However, an extremely high concentration of cortisol (25 μg per ml) still inhibited the effect of 10 U insulin per ml to a slight extent. Addition of puromycin (5 × 10−5 m) abolished the suppressive effect of a physiological concentration of cortisol on insulin stimulated 14CO2 formation from Glucose-1-14C. The mechanism of the observed antagonism between insulin and cortisol at physiological concentrations is assumed to be of the competitive type mediated not by cortisol itself, but by a protein, the formation of which is induced by the action of cortisol.

scholarly journals The clearing-factor lipase activity of isolated fat-cells

1975 ◽  
Vol 146 (2) ◽  
pp. 481-488 ◽  
Author(s):  
A Cryer ◽  
P Davies ◽  
E R Williams ◽  
D S Robinson
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Lipase Activity ◽  
Incubation Medium ◽  
Cell Activity ◽  
Molecular Forms ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell

1. When fat-cells are isolated from the epididymal adipose tissue of 24h-starved rats and incubated at 25 degrees C in the presence of dialysed serum, glucose, insulin, amino acids and heparin, the total clearing-factor lipase acitivity of the incubation system increases progressively over a period of several hours. 2. All of the increase in activity is accounted for by the appearance of enzyme in the appearance of enzyme in the incubation medium and the fat-cell activity does not change significantly. Cycloheximids, at a concentration that prevents protein synthesis, does not affect the appearance of enzyme in the incubation medium, but the fat-cell enzyme activity is decreased in its presence. 3. The magnitude of the increase in total clearing factor lipase activity is unaffected by the omission of heparin from the medium. However, less enzyme is extracted in tis absence and the fat-cell activity increases. Cycloheximide again only affects the rise in cell activity and does not alter the activity in the incubation medium. 4. When serum in the incubation medium is replaced by casein, the distribution of enzyme between the cells and the medium is changed, but the magnitudes of the increases in total enzyme activity are similar. 5. These characteristics of the clearing-factor lipase response of isolated fat-cells differ in several respects from those observed earlier with intact adipose tissue from 24h-starved rats (Robinson & Wing, 1971; Cryer et al., 1973). The differences could be due, in part, to changes in the relative amounts of two different molecular forms of the enzyme that occur during the isolation of the fat-cells.

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