Serum Glycerol Research Articles

Acetyl-coenzyme A carboxylase from avocado (Persea americana) plastids and spinach (Spinacia oleracea) chloroplasts.

Preparations of acetyl-CoA carboxylase [acetyl-CoA-carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] have been obtained from the plastids of avocado (Persea americana) fruit mesocarp and from spinach (Spinacia oleracea) chloroplasts. Both preparations required bovine serum albumin, HCO3-, citrate and glycerol for stabilization. The molecular weight of the avocado enzyme was about 6.5 X 10(5) on the basis of 1 mol of biotin/mol of enzyme, the behaviour of both enzymes on gel filtration being in accord with such a value. Removal of the stabilizing bovine serum albumin resulted in the loss of a biotin-containing fragment from the avocado enzyme. Citrate stabilized the enzyme at 10 mM and activated it optimally at 3.0 mM, effecting an approx. 2-fold increase in Vmax. It is suggested that in vivo the enzyme may be located within the chloroplast lamellae.

The use of an immobilized glycerol dehydrogenase nylon-tube reactor in the determination of glycerol

A continuous-flow system is described that utilizes an immobilized glycerol dehydrogenase nylon-tube reactor integrated into the flow system of a Technicon AutoAnalyzer II for the routine estimation of glycerol in serum and various beverages. Results are compared with determinations made by the solution method that uses the three enzymes glycerokinase, pyruvate kinase and lactate dehydrogenase. These routine trials give reliable and reproducible results with high precision and economy. The glycerol dehydrogenase reactor is stable during intermittent or continuous use for at least 3500 tests. Stored at 4° C when not in use, the reactor is quite stable for several months.

Hyperglycemic effect of an oral load of triglycerides in preterm neonates: 59

Top of pageAbstract A nasogastric load of 2,7 g/kg of lipids with 67 % of medium chain triglycerides and 30 % of grape seeds oil was given at the age of 48 hours to 20 preterm neonates (mean bw = 2164 g ; gest. age : 35 weeks). Its effect on the concentrations of plasma glucose free fatty acids (FFA), serum B-OH-butyrate (BOHB) and lactate was compared to their evolution in 11 control preterm infants (mean bw 2102 g ; gest. age : 35 weeks). The basal levels were similar in both groups. In the supplemented group, plasma glucose increased from (mean ± SD) 57 ± 7 to 74 ± 11 mg/dl at 30 min. (p < 0.001) and to 80 ± 11 mg/dl at 60 min. (p < 0.001) while no significant change was recorded in the control group. At 60 min., serum BOHB had increased in the supplemented group from 339 ± 165 to 631 ± 230 μmol/l (p < 0.01) and it was higher than in the control group : 439 ± 200 μmol/l (p < 0.05). Plasma FFA decreased from 303 ± 178 to 199 ± 90 μlEq/l (p < 0.05) in 60 min. in the control group while no significant change was observed in the supplemented group. Serum lactate decreasedin 30 min. from 1777 ± 809 to 1257 ± 375 μmol/l in the supplemented group (p < 0.05) while the change (from 1820 ± 600 to 1581 ± 438 μmol/1) was not significant in the control group. In 7 supplemented infants, there was no change of serum insulin or glucagon concentration and no change of serum glycerol levels in 6 other supplemented infants. These data suggest that in preterm infants 1)this load of triglycerides can provide glucose and ketone bodies which could be available for the neonatal brain 2)this hyperglycemic effect independant of hormonal influence is probably achieved through gluconeogenesis.

An approach to measuring the in vivo transformation of glycerol to a very low density lipoprotein triglyceride

This paper describes a new method which permits measurement of the steady-state rate of transformation of serum glycerol to a very low density lipoprotein (VLDL) triglyceride in vivo in dogs. Although the turnover of glycerol and the turnover of VLDL triglyceride glycerol have both been previously measured, the rate of transformation of the former into the latter has not. While there is considerable dog-to-dog variation in the absolute turnover and transformation rates, the relationship between the various rates is quite constant. Thus, 13% of the serum glycerol which normal fasting dogs utilize is converted to VLDL triglyceride. The remaining 87% is converted to other products. Also, 28% of VLDL triglyceride glycerol in these dogs is derived from serum glycerol. The balance, 72%, is derived from other sources. The procedure described here can be used to quantitate the contribution of glycerol to VLDL in a number of conditions in which glycerol and (or) VLDL triglyceride metabolism is altered, thereby providing another way to gain insight into the metabolism of VLDL. Even more generally, the principles developed here can be applied to estimate the transformation of other precursors to other products in vivo.

Increased concentrations of free fatty acids and glycerol and altered creatine kinase MM isoenzyme patterns in certain diabetic patients.

We report unusually high concentrations of free fatty acids and glycerol in sera of patients with adult-onset diabetes, and the accompanying alterations in creatine kinase isoenzyme MM patterns associated with such patients. The serum samples with increased free fatty acids also showed increased electrophoretic movement of the MM isoenzyme on cellulose acetate membranes. Fatty acid concentrations found in such samples averaged 9.88 +/- 5.65 (SD) meq/L and the average glycerol concentration was 153 +/- 115 (SD) mg/L. The serum glycerol concentrations correlated with those of the free fatty acids (r = 0.886, slope = 0.309, intercept = 4.76).

Influence of Protein Factors on the Activation of NADP–malate Dehydrogenase by Dithiothreitol

AbstractLeaves of Phaseolus vulgaris L. contained malate dehydrogenase activity dependent on NADP (E. C. 1.1.1.82); it could be detected in extracts only when a dithiol such as dithiothreitol was present. After the addition of dithiothreitol, the activity increased with time, passed through a maximum and then diminished. The activation rate and/or the maximum level of activity were essentially dependent on dithiothreitol concentration, pH, and temperature. The presence of bovine serum albumine or glycerol in the medium decreased the inactivation rate; equivalent results were obtained at low temperatures. A mathematical model was established showing an apparent first‐order rate for activation and inactivation only under conditions of alkaline pH near 8.3. These data allowed us to demonstrate that compounds other than dithiothreitol were necessary for the activation process. Evidence suggested that these compounds were protein factors of low molecular weights which increased the activation rate and the maximum level of activity when added to the incubation medium at pH 7.3. Their efficiency in the enzyme activation was higher at alkaline pH than at acid or neutral pH.

Automated procedure for kinetic measurement of total triglycerides (as glycerol) in serum with the Gilford System 3500.

An automated procedure is used on the Gilford 3500 Computer-Directed Analyzer to measure serum triglycerides indirectly by using aqueous glycerol standards. Most enzymatic methods require long hydrolysis or awkward saponification. The method of Bucolo and David [clin. Chem. 19, 476 (1973)], in which lipase and glycerol kinase are used, is modified. The kinetic procedure described eliminates the need for a serum blank. It uses "Eskalab" bulk reagents and reduces both time and cost per test by measuring the decreasing NADH concentration from the glycerol kinase reaction at 340 nm after enzymatic hydrolysis at room temperature. The change in absorbance of the standard during a 14-s measuring time is used in the ratiometric calculation of the unknowns. The use of a stable aqueous standard that can be reliably and accurately prepared makes this method ideal for the traceability desired by many organizations. Reagent blank drift did not affect the results. A correlation coefficient of 0.991 for comparison with the manual endpoint method and a typical CV of 2.25% show this method to be accurate and reliable.

The Study of Serum Free Fatty Acid, Triglycerides and Glycerol in Congestive Heart Failure, Essential Hypertension and Liver Cirrhosis

The Study of Serum Free Fatty Acid, Triglycerides and Glycerol in Congestive Heart Failure, Essential Hypertension and Liver Cirrhosis

Human glycerol kinase deficiency with hyperglycerolemia and glyceroluria

Two brothers with a previously unidentified syndrome of severe osteoporosis and neuromuscular disease have elevated concentrations of glycerol in serum and urine. A deficiency of glycerol kinase in leukocytes of both patients is described.

Some effects, in baboons, of chronic ingestion of glycerol with sucrose or glucose

Six mature male and six mature female baboons were given fat-free diets high in sucrose or glucose together with glycerol, a chow diet with glycerol, and a fat-free high sucrose diet without glycerol. In the male animals, the concentration of triglyceride, cholesterol, glucose, and glycerol in fasting serum was significantly greater when sucrose and glycerol were given together compared with the other diets. The fasting serum triglyceride and cholesterol were significantly greater in the females on the sucrose + glycerol diet compared to the glucose + glycerol diet. It is suggested that glycerol and fructose (in sucrose) share a metabolic pathway that leads to an enhancement of serum lipid concentrations.

Fluorometric estimation of triglycerides in serum by a modification of the method of Bucolo and David.

An enzymic, flurometric method is described for determination of triglycerides (and glycerol) in blood serum, a modification of the method of Bucolo and David [Clin. Chem. 19, 476 (1973)]. Commercially available reagent kits are used. The rate of disappearance of NADH fluorescence at 460 nm (excitation wavelength, 365 nm) is monitored and related to serum triglyceride concentration, corrected for the content of free glycerol. We compared the results obtained fluorometrically to the ultraviolet spectrophotometric Boehringer Neutral Fat method used at Gentofte Hospital, Copenhagen. Instrument response and concentration were linearly related in the range 0.27 to 2.7 mmol of triglycerides per liter of serum with the fluorometric method. The CV was 0.9% for the fluorometric method, 3.7% for the spectrophotometric procedure. The fluorometric method requires less reagents, time, and calculations than does the spectrophotometric method.

Metabolic and cardiovascular responses to norepinephrine in trained and nontrained human subjects.

Forty young male adults, aged 18-30 yr, with maximal oxygen intake (VO2 max) varying between 35 and 76 ml-kg-1-min-1 were studied. The fasting subjects were perfused for 15 min with saline and thereafter for 30 min with norepinephrine (0.1 mug/kg per min). Blood variables were determined at the end of slaine perfusion, at 15 and 30 min during norepinephrine perfusion and 15 min after the end of NE perfusion. Trained subjects are characterized by lower basal plasma glucose and insulin concentration. NE perfusion produced a larger increase in plasma glucose in the trained subjects. Levels of insulin in the postperfusion period were smaller in the trained group. Serum free fatty acids (FFA) and glycerol increased less in the trained subjects during NE perfusion and this difference persisted in the post-perfusion period. During NE perfusion, blood lactate increased only in the nontrained subjects. Initial heart rate and blood pressure were lower in trained subjects but, during NE perfusion, elevated levels of blood pressure and decreased levels of heart rate were comparable in both groups. Because of similarities in responses to exercise and to NE in trained subjects, the results of the present study suggest a possible role for NE in exercise training.

A semi-automated enzymatic assay for free glycerol and triglycerides in serum or plasma

1. A relatively inexpensive semi-automated enzymatic procedure is described for the determination of total glycerol with an Auto Analyzer. Free glycerol is determined without saponification in a deproteinized supernatant. 2. The dilution of triglyceride samples during preparation is such that the samples during preparation is such that the samples can be quantified directly from the free glycerol standards by multiplying by 100. 3. A pyruvate kiluent solution is used in the triglyceride sample preparation to increase the precision by improving the accuracy in determining blank optical densities. 4. The end-point reaction is complete in eight minutes, and the assay is linear up to 6 mg% free glycerol or 600 mg% triglycerides. The within-run and between-run coefficients of variation were both 1.5% for the glycerol assay, and 1.0% and 4.3% for the triglyceride assay. The mean recovery of added glycerol was 100.7% and 102.3% for the glycerol and triglyceride assays respectively.

Serum Glycerol and Hepatic Glycerokinase Activity in the Carbohydrate-Sensitive BHE Strain of Rat

SummarySerum free glycerol and hepatic glycerokinase and L-a-glycerophos-phate dehydrogenase were measured in nonfasted, 75-day-old Wistar and carbohydrate-sensitive BHE rats. Serum free glycerol levels and glycerokinase activity were found to be elevated in the BHE strain. These results suggest that hepatic glycerol utilization by the BHE rat is being determined by factors other than the kinetics of the first glycerol-metabolizing step.

Surgical reduction of adipose tissue in the male Sprague-Dawley rat

The lipostatic theory of regulation of adipose tissue mass was tested by a method for surgical reduction (adipectomy) of 24% of the total body fat of nonobese adult Sprague-Dawley rats, as judged from carcass analyses. The reduction persisted during an observation period of 12 wk without any evidence of altered food intake, weight gain, or compensatory hypertrophy or hyperplasia of adipose tissue compared with sham-operated controls. No changes were found in serum free fatty acids, glycerol, triglycerides, cholesterol, or insulin between adipectomized and control animals, implying an intact quantitative function of the remaining adipose tissue. It is concluded that the size of the adipocytes rather than the number is important for a presumed lipostatic regulation of adipose tissue mass in the adult male Sprague-Dawley rat.

ChemInform Abstract: HYPOCHOLESTEROLEMIC ACTIVITY OF 1,3‐BIS(SUBSTITUTED PHENOXY)‐2‐PROPANONES

AbstractPhenole (I) reagieren mit Epichlorhydrin (II) in Gegenwart von NaOH zu den Bis‐ äthern (III), die mit DMSO/Carbodiimid zu den Keto‐diäthern (IV) oxidiert werden.

Purification and characterization of lipoprotein lipase from human heart

Human heart lipoprotein lipase was purified by affinity chromatography on heparin-Sepharose 4B. When crude extracts of heart acetone powder were applied to columns, about 40% of total lipase activity was bound to the gel and then eluted with 1.5 M NaCl. At this stage the eluted enzyme was purified 1900-fold. Disc gel electrophoresis yielded a single protein band corresponding with lipolytic activity. Minimum molecular weight of the protein was 60,000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The purified enzyme was highly unstable; however, its activity could be partially stabilized at −20°C by bovine serum albumin, glycerol, or ethylene glycol. The activity of the purified enzyme (i) had a pH optimum between 7.8 and 8.0; (ii) required serum for full enzymatic activity; apoC-II could be substituted for serum; (iii) was inhibited by apoC-I in the presence of activated substrate; (iv) was markedly inhibited by NaCl; and (v) was stimulated by heparin.

Hypocholesterolemic activity of 1,3-bis(substituted phenoxy)-2-propanones.

A series of 1,3-bis(substituted phenoxy)-2-propanones was found to be active hypocholesterolemic agents at 10 mg/kg/day. The p-chloro- and p-methyl-substituted phenoxy compounds possess the highest activity. These compounds did not possess the estrogenic and antifertility activities of the related previously reported derivatives of the bis(beta-phenylethyl) ketone series. The 1,3-bis(p-methylphenoxy)-2-propanone (7) also lowered serum triglycerides and glycerol which appeared to be due to increased levels of serum lipase and reduced activity of liver lipase. There was reduced incorporation of free fatty acids into complex lipids by the liver. Cholesterol was excreted faster in the treated animals.

Changes in plasma non esterified fatty acids and serum glycerol in pregnancy.

Changes in plasma nonesterified fatty acids (NEFA) and serum glycerol in pregnancy were examined in a semi-serial study of 85 women. A preliminary study showed that it was almost impossible to achieve standardized conditions for sampling, and the compromise of taking a single venous sample without stasis, after 30 minutes rest and about 12 hours fasting, was adopted. Although there were large individual variations the patterns of change were, in general, the same for NEFA and glycereo although the two were not closely correlated. There was no +convincing change before 30 weeks of pregnancy but both increased in the last ten weeks, fell sharply in the first week post partum, and then rose again to late pregnancy levels by 6 weeks post partum before falling to non-pregnant levels by between 3 and 6 months post partum. Those patterns of change are in broad accordin with changes of fat storage and lipolysis associated with the reporoductive cycle. Changes in the patterms of NEFA were triviax the only significant alteration was a small rise in the proportion of C16:0 (palmitic) in late pregnancy.

Redistribution of regional cerebral blood flow after glycerol infusion in acute cerebral infarction.

Article abstract Regional cerebral blood flow and blood volume were measured before and after intravenous infusion of 10 percent glycerol in normal saline in a series of 24 patients with receni. ischemic or hemorrhagic cerebral infarction. Measurements were made by serial intracarotid injection of xenon 133 and technetium 99m and by the use of the gamma camera. Regional cerebral blood flow and blood volume, prior to glycerol infusion, were reduced more in patients with hemorrhagic infarction than in those with ischemic infarction. Border zones of relative hyperemia were present in both groups. After glycerol infusion (50 g), mean serum glycerol levels rose to 33.1 millimols, cerebrospinal fluid pressure was reduced, and regional cerebral blood flow and blood volume were increased in the ischemic zone of both groups, with a redistribution of blood from the hyperemic to the ischemic zones.