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Biomedical subjects

P Belfrage

Publications and source records attributed to P Belfrage.

At least 127 records · Page 7Linked to original sources
PubMed1979

Continuous monitoring of free fatty acid release from adipocytes by pH-stat titration.

A methods for direct and continuous monitoring of free fatty acid release in adipocyte suspensions is described. Using a pH-stat apparatus the protons from the released free fatty acids are continuously titrated and the accumulated amount of OH- added is monitored on a recorder against time, the slope thus indicating the rate of free fatty acid release. Sinc pH is kept constant, an incubation medium with a low buffering capacity can be used, which gives the method a high sensitivity. Under the conditions described, free fatty acid release from 5% of maximal norepinephrine stumulation of rat adipocytes can be accurately measured and the kinetics can be followed over extended periods of time.

Adipose Tissue↗
PubMed1978

Enzymes catalyzing the hydrolysis of long-chain monoacyglycerols in rat adipose tissue.

Acetone-ether preparations of epididymal fat pads from fasted or fed rats contained two enzymes catalyzing the hydrolysis of long-chain monoacylglycerols. The enzymes were identified as monoacylglycerol lipase (Tornqvist, H. and Belfrage, P., (1976) J. Biol Chem. 251, 813--819) and lipoprotein lipase by their apparent pI values after electrofocusing in non-ionic detergent, selective inhibition properties, substrate specificity and positional specificity. It was estimated that monoacylglycerol lipase accounted for about 90% of the total monoacylglycerol-hydrolyzing activity in acetone-ether preparations from fasted and 70% from fed rats. Its enzyme activity did not change with the nutritional state in contrast to that of lipoprotein lipase. The latter enzyme hydrolyzed 2-monoacylglycerols at a much lower rate than the 1(3)-isomers. Monoacylglycerol lipase was located almost entirely in the adipocytes, thus most of the enzyme activity towards monoacylglycerols in the adipose tissue was found in this site. Fractionated sucrose homogenates of rat epididymal fat pads also contained a third enzyme with monoacylglycerol-hydrolyzing activity, identified as hormone-sensitive lipase by its pI, selective inhibition properties and substrate specificity. It was estimated that hormone-sensitive lipase accounted for less than 20% of the total activity against monoacylglycerols in these tissue preparations from fasted rats. Over-all quantitative estimations emphasized the dominant role of monoacylglycerol lipase over the other two enzymes in the hydrolysis of monoacylglycerols.

Adipose Tissue↗
PubMed1978

Removal of nonionic detergent from proteins fractionated by electrofocusing.

The nonionic detergent Nonipol TD 12 (an alkyl polyoxyethylene alcohol) has been removed from solubilised proteins after their fractionation by electrofocusing. Following electrofocusing in nonionic detergent an anionic or cationic detergent was added to the focussing medium and the focusing was allowed to continue. The ionic detergent formed mixed micelles with the nonionic detergent. Thus charged, the mixed micelles migrated to either electrode, removing nonionic detergent from the fractionated proteins. Applying this technique to an adipose tissue preparation, detergent-inhibited activity of a lipolytic enzyme was restored and the binding of adenosine 3':5'-cyclic monophosphate (cyclic AMP) to a protein kinase was increased.

Adipose Tissue↗
PubMed1978

Identification and some characteristics of the enzyme protein of the hormone-sensitive lipase from rat adipose tissue.

A tri-, di-, and monoacylglycerol-hydrolyzing enzyme from rat adipose tissue has been detergent-solubilized and separated from monoacylglycerol lipase (H. Tornqvist and P. Belfrage, 1976, J. Biol. Chem. 251, 813-819) and lipoprotein lipase by use of ion-exchange chromatography, broad and narrow pH range electrofocusing and gel chromatography. The final preparation contained several different proteins. One of these, with an apparent minimum molecular weight of 86,000 by SDS-gel electrophoresis, was identified as the enzyme protein of hormone-sensitive lipase: a) the enzyme activity was reproducibly stimulated 50-100% by incubation with cyclic AMP-dependent protein kinase, cyclic AMP and ATP-Mg2+; b) the relative intensity of the Mw 86,000 protein band, and only this, closely paralleled the enzyme activity during narrow pH range electrofocusing and during subsequent gel chromatography of the electrofocusing enzyme peak fraction; c) only the Mw 86,000 protein extensively incorporated 32p from [gamma-32P]ATP after incubation with protein kinase and cyclic AMP. The pI of the enzyme was 6.7, it had the same Stokes radius on Sephadex G 200 as IgG and was 50% inactivated by 10 micron HgCl2, 20 micron PCMB, 50 micron DFP, 10 mM NaF and non-ionic detergents above their critical micellar concentration.

Adipose Tissue↗
PubMed1978

Effects of acetate, acetaldehyde, and ethanol on lipolysis in isolated rat adipocytes.

The effects of different concentrations of acetate, acetaldehyde, and ethanol, alone or in combination, on the lipolysis rate, measured as glycerol release, were studied in isolated adipocytes from fed or fasted rats, in the basal state and at various levels of norepinephrine stimulation. Acetate inhibited the glycerol release in a dose-dependent manner (congruent to 10% inhibition at 2 mM, 25--70% at 10 mM) with the most marked effects at low to moderate norepinephrine concentratione and at maximal (100 ng/ml) hormone stimulation. Ethanol, up to 100 mM concentration, had no effect on the lipolysis rate. Acetaldehyde, up to 1 mM concentration, had no reproducible effect. Ethanol, acetaldehyde, and acetate in combination inhibited glycerol release to an extent similar to that of acetate alone.

Acetaldehyde↗
PubMed1977

Alterations of lipid metabolism in healthy volunteers during long-term ethanol intake.

Nine young, healthy male volunteers were given ethanol (75 g/day) for 5 weeks. The ethanol was divided into five daily doses and taken so that blood ethanol levels never exceeded 0.04% (w/v). During the latter part of the ethanol intake period, there was a significant, transient increase of plasma triglyceride (TG) concentrations followed by reduction to normal levels. A three-fold increase of lipoprotein lipase activity (LLA) occurred in biopsy specimens of adipose tissue. An increase of alpha-lipoprotein concentrations, which correlated significantly with the decrease in plasma TG levels and the increase in adipose LLA, was also observed during the ethanol intake period. No changes were observed in plasma cholesterol and beta-lipoprotein levels. A transient, three-fold increase of TG concentrations occurred in liver biopsy specimens. Ultrastructural and cytochemical examinations of the biopsy specimens showed hyperplasia of the smooth endoplasmic reticulum, and increased canallicular activity of gamma-glutamyl transferase (gamma-GT) activity in most subjects towards the end of and after the ethanol intake period. Serum gamma-GT levels also increased significantly.

Adipose Tissue↗
PubMed1977

General anaesthesia or lumbar epidural block for caesarean section? Effects on the foetal heart rate.

Caesarean section was performed in 10 patients under general anaesthesia and in 10 other patients under epidural block. The foetal heart rate was monitored continuously during anaesthesia and operation with a scalp electrode and a cardiotocograph. There was no major difference between the two anaesthetic techniques in their effect on the foetal heart rate. The most common finding was a reduction of the beat-to-beat variation. The operative time was longer in the epidural group than in the general anaesthesia group, due to a higher frequency of Pfannenstiel incisions and repeat caesarean sections in the epidural group. Clinically, all newborns seemed to be unaffected, with normal Apgar scores. Epidural block seems to be a good alternative to general anaesthesia for caesarean section, particularly when a long operative time is expected.

Anesthesia, Epidural↗
PubMed1976

Purification and some properties of a monoacylglycerol-hydrolyzing enzyme of rat adipose tissue.

A monoacylglycerol-hydrolyzing enzyme has been purified 2500-fold from rat adipose tissue. The key step was the solubilization of the enzyme, presumably as an enzyme-detergent complex, by sonication with a nonionic polyoxyethylene alcohol detergent. The purification was achieved by ion exchange and gel chromatography, and isoelectric focusing, in the presence of detergent. By sodium dodecyl sulfate gel electrophoresis the enzyme protein was more than 85% pure. This method indicated a minimum molecular weight of 32,900. The preliminary amino acid composition, excluding tryptophan, could best be fitted with a value of 31,800. The purified enzyme had a pI of 7.2, an estimated Stokes radius of 39 A by gel chromatography and a pH optimum of 8.0. Enzyme stability was highly dependent on presence of detergent and free sulfhydryl groups. The enzyme was responsible for the main monoacylglycerol- but only a small part of the p-nitrophenylacetate-hydrolyzing activity of crude adipose tissue extracts and hydrolyzed 1(3)- and 2-monooleoylglycerol at equal rates. Under the assay conditions used it did not catalyze the hydrolysis of emulsified trioleoylglycerol, micellar or emulsified dioleoylglycerol, emulsified cholesterol oleate or micellar lysophosphatidylcholine. It is possible that the enzyme may be a specific monoacylglycerol hydrolase.

Adipose Tissue↗
PubMed1976

Uptake of bupivacaine (Marcaine) in liver and lung after intramuscular administration in the dog.

The uptake of bupivacaine in the liver and lung of the dog was studied 10,20,30 and 60 min after intramuscular injection of the drug. It was possible to quantify this uptake by combining measurements of concentrations and flows. The administration of bupivacaine (0.75 mg/kg b.w.) did not result in any significant circulatory changes. Arterial bupivacaine concentrations showed major variations, indicating interindividual differences in absorption rate. Lung uptake after 10 min was high in two dogs with initially high blood concentrations of bupivacaine, but low after 20 min or longer. The other dogs showed little or no uptake. Mean hepatic bupivacaine uptake was about 50% of the total dose during the first hour after injection, this indicates the central role of the liver in eliminating bupivacaine even during the initial period following administration. The hepatic extraction ratio showed interindividual variations, but the mean value of about 55% was constant throughout the observation period. This is in agreement with earlier findings indicating a first-order elimination of bupivacaine.

Animals↗
PubMed1976

Lumbar epidural analgesia in labour. A clinical analysis.

Lumbar epidural block was given for pain relief to 296 women in labour. Bupivacaine was used as the analgesic agent and the technique is described in detail. Satisfactory analgesia was obtained in 92% of the cases during the first stage of labour and in 84% during the second stage of labour. The frequency of instrumental deliveries and of occipitio-posterior position increased but the clinical condition of the newborn seemed to be unaffected.

Anesthesia, Epidural↗
PubMed1976

Epidural analgesia in labour. IV. Influence on uterine activity and fetal heart rate.

The influence of epidural block with bupivacaine (Marcaine-adrenalin) on fetal heart rate, uterine activity, and the frequency and intensity of contractions was studied in twenty-five nulliparae at term. Uterine activity was found to decrease during the first 30 minutes following epidural block. In the time interval 30 to 40 minutes after epidural block uterine activity increased again and attained the same level as during the last 10 minutes before analgesia. The frequency of uterine contractions did not decrease after the block. The lower levels of uterine contractility were due only to a lower amplitude of the contractions. The regularizing effect of epidural analgesia on incoordinate uterine action was noted. The recording of fetal heart rate in the time interval studied revealed no pathological findings. Mode of delivery, mean labour duration and Apgar scores after epidural block were comparable with earlier studies of a larger patient population. This study suggest that epidural analgesia does not induce any important changes in fetal heart rate but temporarily decreases uterine activity.

Adolescent↗
PubMed1976

Determination of protein in adipose tissue extracts.

An accurate and sensitive method for determination of protein in adipose tissue extracts based on a scaled-down version of the method of Lowry et al. (1951, J. Biol. Chem. 193, 265-275) is described. Protein is quantitatively precipitated by trichloroacetic acid with a nonionic detergent as a bulk-increasing substance and the precipitate is extracted with an organic solvent. This interference caused by lipids, sulfhydryl reagents, and several other compounds is eliminated. The accuracy of the determination of dilute reference protein solutions (2-20 mug/ml) is demonstrated.

Adipose Tissue↗
PubMed1975

Lumbar epidural analgesia with bupivacaine in labor. Drug concentration in maternal and neonatal blood at birth and during the first day of life.

Lumbar epidural analgesia with bupivacaine was administered to 33 women for relief of pain during labor. At delivery blood samples were drawn from the umbilical cord vessels and from a maternal peripheral vein. Blood samples were also collected from the noenate and its mother, 1, 4, and 20 hours after delivery. Analyses of bupivaccaine concentrations were carried out in all samples with a gas-chromatographic technique. The drug concentration in the umbilical vein (UV) was usually higher than the corresponding umbilical artery value (UA), but with increasing time interval between the last bupivaccaine infection and delivery the UA/UV drug concentration ratio rose. After delivery the rate of drug decline in blood was similar in mother and newborn infant. The clinical condition of the infant was unrelated to the drug concentration in the umbilical cord vessels.

Adolescent↗