Hans J. Grav

Metabolic effects of thia fatty acids.

Thia substituted fatty acids are saturated fatty acids which are modified by insertion of a sulfur atom at specific positions in the carbon backbone. During the last few years pleiotropic effects of the 3-thia fatty acid tetradecylthioacetic acid have been revealed. The biological responses to tetradecylthioacetic acid include mitochondrial proliferation, increased catabolism of fatty acids, antiadiposity, improvement in insulin sensitivity, antioxidant properties, reduced proliferation and induction of apoptosis in rapidly proliferating cells, cell differentiation and antiinflammatory action. These biological responses indicate that tetradecylthioacetic acid changes the plasma profile from atherogenic to cardioprotective. As a pan-peroxisome proliferator-activated receptor ligand, tetradecylthioacetic acid regulates the adipose tissue mass and the expression of lipid metabolizing enzymes, particularly those involved in catabolic pathways. In contrast, circumstantial evidences suggest that peroxisome proliferator-activated receptor-independent metabolic pathways may be of importance for the antioxidant, antiproliferative and antiinflammatory action of tetradecylthioacetic acid.

Effects of improved nutrition in pregnant reindeer on milk quality, calf birth weight, growth, and mortality

A group of 35 pregnant reindeer (Rangifcr tarandus) was divided into two groups in mid-February. Until calving in May one of the groups (L) received lichen ad lib., while the other group (IN) received an improved diet, rich in protein and minerals. After calving both groups received the same improved diet. In both groups it was distinguished between young ( 3 years) animals. At the start of the experiment the body weight of L-young animals was 58.5 ± 4.6 kg, IN-young 56.2 ± 2.8 kg, L-old 70.3 ± 6.0 kg and IN-old 68.2 ± 4.8 kg. At calving the weights of the same animals were 55.9 ± 4.5 kg (L-young), 68.1 ± 2.5 (IN-young), 70.0 ± 6.9 kg (L-old) and 81.6 ± 6.8 kg (IN-old). Birth weight of IN-young calves was 4.5 ± 0.7 kg and of L-young calves 3.7 ± 0.5 kg. Birth weight of IN-old calves was 5.7 ± 0.8 kg and of L-old calves 4.4 ± 0.6 kg. The birth weight of the calves in all groups was correlated to the weight of the female just prior to calving. Growth rates in all but the IN-old group were not different, the IN-old group showing a significantly higher growth rate than the other groups. In mid-September, however, the average body weight for the calves from the L and IN-groups did not differ significantly. Neither chemical composition nor total energy content of the milk differed significantly between the groups. Total mortality in the L-group was 28% as compared to 7% in the IN-group. Two females in the IN-old group had not given birth at the end of the experimental period. Virkningen av bedret ernaering til drektige reinsimler pa melkekvalitet, kalvenes fodselsvekt, vekst og dodelighet. Abstract in Norwegian / Sammendrag: En flokk pa 35 drektige reinsimler (Rangifer tarandus) ble delt i to grupper i midten av februar. Frem til kalving i mai ble den ene gruppen gitt lav ad lib. (L-gruppe), mens den andre gruppen ble tilleggsforet med 2 kg RF - 71/dag (IN-gruppe). Etter kalving ble begge gruppene gitt 2 kg RF - 71/dag. Innen begge gruppene ble det skilt mellom unge ( 3 ar) simler. Ved forsokets start var kroppsvekten for unge simler ca. 57 kg, og for gamle simler ca. 69 kg, i begge ernaeringsgruppene. Ved kalving var kroppsvekten for unge simler 55.9 ± 4.5 kg (L-gruppe), og 68.1 ± 2.5 kg (IN-gruppe) mens kroppsvekten for gamle simler var 70.0 ± 6.9 kg (L-gruppe) og 81.6 ± 6.8 kg (IN-gruppe). Fodselsvekt for kalver etter IN-unge simler var 4.5 ± 0.7 kg, og 3.7 ± 0.5 kg for kalver etter L-unge simler. De tilsvarende fodselsvektene for kalver etter gamle simler var 5.7 ± 0.8 kg (IN-gruppe) og 4.4 ± 0.6 kg (L-gruppe). Fodselsvektene var korrelert til simlenes kroppsvekt like for kalving. Kalveveksten i de forste tre ukene etter fodselen var signifikant hoyere for kalver etter IN-gamle simler, sammenlignet med kalveveksten i de ovrige tre gruppene, som ikke var innbyrdes signifikant forskjellige. I midten av september var det ingen signifikante forskjeller i kalvenes kroppsvekt gruppene imellom. Det var ingen signifikante forskjeller hverken i totalt energiinnhold eller i kjemisk sammensetning av melken fra simlene i de to ernaeringsgruppene. Total dodelighet for kalver i L-gruppen var 28% mot 7% i IN-gruppen i lopet av de tre forste ukene etter fodselen. To av de gamle simlene i IN-gruppen hadde ikke kalvet ved forsokets slutt. Kantavien porovaatimien parannetun ravinnon vaikutus maidonlaatuun, vasojen syntymapainoon, kasvuun ja kuolleisuuteen. Abstract in Finnish / Yhteenveto: 35 kantavan porovaatimen (Rangifer tarandus) lauma jaettiin kahteen ryhmaan helmikuun puolivalissa. Vasomiseen saakka toukokuussa annettiin toiselle ryhmalle jakalaa ad. Ub. (L-ryhma), kun taas toinen ryhma sai lisaravintona 2 kg RF-71 rehua paivassa (IN-ryhma). Vasomisen jalkeen annettiin molemmille ryhmille 2 kg RF-71 rehua paivassa. Molemmissa ryhmissa erotettiin nuoret ( 3-vuotiaat) vaatimet toisistaan. Tutkimuksen alkuvaiheessa oli nuorten vaatimien ruumiinpaino n.57 kg, ja vanhojen vaatimien n.69 kg, molemmissa ravintoryhmissa. Vasomisen aikana oli nuorten vaatimien ruumiinpaino 55,9 ± 4,5 kg (L-ryhma), ja 68,1 ± 2,5 kg (IN-ryhma), kun taas vanhojen vaatimien ruumiinpaino oli 70,0 ± 6,9 kg (L-ryhma) ja 81,6 ± 6,8 kg (IN-ryhma). Vasojen syntymapaino IN-nuorten vaatimien ryhmassa oli 4,5 ± 0,7 kg, ja 3,7 ± 0,5 kg L-nuorten vaatimien ryhmassa. Vastaavat syntymapainot vanhojen vaatimien vasoilla olivat 5,7 ± 0,8 kg (IN-ryhma) ja 4,4 ± 0,6 kg (L-ryhma). Syntymapainot olivat vastaavuussuhteessa vaatimien ruumiinpainoon vahaa ennen vasomista. IN-vanhojen vaatimien vasojen kasvu ensimmaisten kolmen viikon aikana syntyman jalkeen oli merkittavasti korkeampi, verrattuna niiden kolmen muun ryhman vasankasvuun, jotka eivat olleet keskenaan merkittavan erilaisia. Vasojen ruumiinpainossa ryhmien kesken ei ollut mitaan merkittavia eroavaisuuksia syyskuun puolivalissa. Naiden kahden ravintoryhman vaatimien maidossa ei ollut mitaan merkittavia eroja kokonaisuudessa ravinnon sisaltoon eika kemialliseen kokoonpanoon nahden. Vasojen kokonaiskuolleisuus L-ryhmassa oli 28% ja IN-ryhmassa 7% kolmena ensimmaisena viikkona syntyman jalkeen. Kaksi vanhaa vaadinta IN-ryhmassa ei ollut vasonut tutkimuksen lopussa.

Lipid profiles of Helicobacter pylori colony variants.

A phase variation in Helicobacter pylori has been previously described. In one phase the bacterium had a cell wall lipid content typical for gram‐negative bacteria (HpL), whereas in the other phase the bacterium was found to have a cell wall with increased amounts of lysophospholipids (HpS). The conversion is spontaneous, but could also be induced by acid (HpSind) and was associated with in vitro release of Vac A and urease. The purpose of the present study was to determine the full phospholipid content of the cell wall to indicate a molecular mechanism of the colony variation. There were no appreciable differences between the lipid profiles of HpS and HpSind, while there were major differences between HpL and the S‐variant. In the S‐variant, lysophospholipids constituted about 50% of the total phospholipids, as compared to less than 2% in the L‐variant. The proportion of total and individual cholesteryl glucosides also showed considerable changes. HpL was dominated by the phosphate‐linked cholesteryl glucoside (72%) while the acylated cholesteryl glucoside was the main cholesteryl glucoside of the S‐variant (65%). Our results demonstrate a dramatic change in cell wall properties after acid induction and spontaneously in vitro, and suggest some molecular mechanisms for this variation from an in vitro non‐virulent to a virulent variant.

Gas chromatographic measurement of 3- and 4-thia fatty acids incorporated into various classes of rat liver lipids during feeding experiments.

A practical procedure is described for the quantitative measurement of the amount of acyl units derived from tetradecylthioacetic acid (effecting hypolipemia in rats) and tetradecylthiopropionic acid (effecting hyperlipidemia). The procedure involves three main successive steps: (1) extraction; (2) solid-phase lipid class separation yielding free fatty acids, phospholipids, triacylglycerides, cholesterol esters, and diacylglycerides without crosscontamination; and (3) gas chromatography of hydrolyzed lipids derivatized to picolinyl esters, combined with unambiguous identification by gas chromatography-mass spectrometry. The overall recoveries of heptadecanoyl lipids added as internal standards during extraction were 94-96%, except for cholesteryl heptadecanoate where the recovery was 60% owing to incomplete hydrolysis. Recoveries of thia fatty acids from samples spiked with these compounds were 95%. Flame-ionization response factors were found to be 0.92 and 0.81 for the tetradecylthioacetic acid and tetradecylthiopropionic acid picolinyl esters, respectively, compared to that of heptadecanoic acid. The lower limit of quantitation was 25 pmol as injected. Measurement of the amount of thia fatty acyl units in rat plasma and in liver lipids 4 h after administration of single doses by gastric intubation indicated efficient absorbtion and rapid incorporation into liver lipids, particularly in the phospholipid fraction. Both plasma clearance and channelling into lipids was slower for the 4-thia fatty acid.

Oxidative capacity of tissues contributing to thermogenesis in eider (Somateria mollissima) ducklings: changes associated with hatching

Summary1.The development of liver and skeletal muscle oxidative capacities during hatching of the common eider (Somateria mollissima) in the Arctic has been investigated by monitoring tissue cytochrome c oxidase activity.2.The specific activity of the liver enzyme did not change as the embryo underwent hatching, nor during subsequent growth of the duckling into adulthood.3.Thigh muscle enzyme specific activity increased by a factor of 3.4 during the 24 h prehatching period, remained elevated for at least 48 h after hatching, and then returned to the embryonic (−24 h) level in adults.4.Histochemically visualized NADH-tetrazolium reductase of a typical red thigh muscle, M. vastus lateralis, showed a distinct increase in activity as the hatching process progressed to completion.5.Electron microscopy of sectioned M. vastus lateralis revealed a dramatic increase in the density of the myofibrillar structure (number of mitochondrial profiles per unit area), and in the surface area of mitochondrial crista membranes in the course of the 48 h interval from 1 day prehatching to 1 day after hatching.6.The significance of these changes for the scaling of thermoregulatory heat generation in the newly hatched eider duckling is discussed.

Acute modulation of rat hepatic lipid metabolism by sulphur-substituted fatty acid analogues

A single oral dose of two 3-thia (3-thiadicarboxylic and tetradecylthioacetic acids) and of 4-thia (tetradecylthiopropionic acid) fatty acids were administered to normolipidemic rats and their effects on lipid metabolism over a 24 hr period were studied. All three thia fatty acids could be detected in plasma 2 hr after treatment. Tetradecylthioacetic and tetradecylthiopropionic acids were detected in different hepatic lipid fractions but were incorporated mainly into hepatic phospholipids. Two hours after administration hepatic mitochondrial beta-oxidation and the total liver level of long-chain fatty acyl-CoA increased with a concomitant decrease in saturated fatty acids, total hepatic malonyl-CoA and plasma triacylglycerol levels in the 3-thia fatty acid groups. Tetradecylthiopropionic acid administration caused a decrease in mitochondrial beta-oxidation and an increase in plasma triacylglycerol at 24 hr. The activities of key lipogenic enzymes were unaffected in all treatment groups. Plasma cholesterol level was reduced only at 8 hr in 3-thiadicarboxylic acid treated rats although 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase was suppressed already at 2, 4, 8 and 12 hr. The results show that thia fatty acids are rapidly absorbed and are systemically available after oral administration but the 3-thia fatty acids reached systemic circulation more slowly and less completely than the 4-thia fatty acid. Very low levels of the thia fatty acids are detected in plasma 24 hr after a single administration. They are incorporated into all hepatic lipid classes, especially phospholipids. Rapid incorporation of a non beta-oxidizable thia fatty acid into hepatic lipids may cause a diversion of other fatty acids from glycerolipid biosynthesis to mitochondrial beta-oxidation. Stimulation of mitochondrial beta-oxidation and suppression of HMG-CoA reductase are primary events, occurring within hours, after 3-thia fatty acid administration. The hypotriglyceridemic effect of the 3-thia fatty acids observed at 2-4 hr is independent of the activities of key lipogenic and triacylglycerol synthesising enzymes.

Oxidative properties of brown adipose tissue mitochondria from rats, guinea-pigs and hedgehogs

Abstract 1. 1. Phosphate acceptor control can be demonstrated with brown adipose tissue mitochondria from rats, guinea-pigs and hedgehogs under essentially similar conditions in vitro . 2. 2. Factors of special importance are a proper pH, presence of serum albumin and high energy nucleotides. 3. 3. In presence of serum albumin ATP was practically as potent as GTP in tightening the coupling of respiration to phosphorylation with mitochondria from guinea-pigs. With mitochondria from rats ATP was distinctly less effective than GDP or GTP and with mitochondria from hedgehogs only guanine nucleotides had this property. 4. 4. The physiological implications of these findings are discussed.

Effects of chain length and sulphur position of thia fatty acids on their incorporation into phospholipids in 7800 C1 hepatoma cells and isolated rat hepatocytes, and their effects on fatty acid composition of phospholipids

Incorporation of thia fatty acids and their effects on the fatty acid composition in phospholipids has been investigated in 7800 C1 hepatoma cells and cultured hepatocytes. 3-Thia fatty acids of chain lengths from dodecyl-to hexadecyl-thioacetic acid were incorporated into phospholipids during a 3-day incubation. Longer and shorter 3-thia fatty acids were barely detectable. Tetradecylthioacetic acid, 3-thia stearate, and their delta9- desaturated derivatives were maximally incorporated into whole-cell phospholipids. The amount of tetradecylthioacetic acid incorporated into phospholipids of hepatoma cells remained almost identical in cells cultured for 3 days or adapted over a period of 1 year. Delta9-desaturated metabolites of long chain thia fatty acids (C13-to C16-S-acetic acid) were identified by GC-MS in phospholipids. 3-Thia stearate appeared to be the best substrated for delta9 desaturase. Incubation of hepatoma cells with thia fatty acids led to alterations in the amount of normal fatty acids in total phospholipids. The amounts of 16:0 and 18:1 decreased and 18:2 (n-6) and 20:5 (n-3) increased. Changes in the normal fatty acid composition of phospholipids were seen both with thia acids incorporated into phospholipids and those not incorporated. These effects, therefore, may be only partially dependent on displacement of normal fatty acids by thia fatty acids. Morris 7800 C1 hepatoma cell acyl-CoA synthetase (ACS) and peroxisomal acyl-CpA oxidase (ACO) were induced by thia fatty acids of all chain lengths, and with the sulphur atom(s) in different positions. Control experiments with hepatocytes revealed a similar incorporation of thia fatty acids in these physiologically more normal cells.

Enhanced hepatic fatty acid oxidation and upregulated carnitine palmitoyltransferase II gene expression by methyl 3-thiaoctadeca-6,9,12,15-tetraenoate in rats

This study reports the effects of a novel polyunsaturated 3-thia fatty acid, methyl 3-thiaoctadeca-6,9,12,15-tetraenoate on serum lipids and key enzymes in hepatic fatty acid metabolism compared to a saturated 3-thia fatty acid, tetradecylthioacetic acid. Palmitic acid treated rats served as controls. Fatty acids were administered by gavage in daily doses of 150 mg/kg body weight for 10 days. The aim of the present study was: (a) To investigate the effect of a polyunsaturated 3-thia fatty acid ester, methyl 3-thiaoctadeca-6,9,12,15-tetraenoate on plasma lipids in normolipidemic rats: (b) to verify whether the lipid-lowering effect could be consistent with enhanced fatty acid oxidation: and (c) to study whether decreased activity of esterifying enzymes and diversion to phospholipid synthesis is a concerted mechanism in limiting the availability of free fatty acid as a substrate for hepatic triglyceride formation. Repeated administration of the polyunsaturated 3-thia fatty acid ester for 10 days resulted in a reduction of plasma triglycerides (40%), cholesterol (33%) and phospholipids (20%) compared to controls. Administration of polyunsaturated and saturated 3-thia fatty acids (daily doses of 150 mg/kg body weight) reduced levels of lipids to a similar extent and followed about the same time-course. Both mitochondrial and peroxisomal fatty acid oxidation increased (1.4-fold- and 4.2-fold, respectively) and significantly increased activities of carnitine palmitoyltransferase (CPT) (1.6-fold), 2,4-dienoyl-CoA reductase (1.2-fold) and fatty acyl-CoA oxidase (3.0-fold) were observed in polyunsaturated 3-thia fatty acid treated animals. This was accompanied by increased CPT-II mRNA (1.7-fold). 2,4-dienoyl-CoA reductase mRNA (2.9-fold) and fatty acyl-CoA oxidase mRNA (1.7-fold). Compared to controls, the hepatic triglyceride biosynthesis was retarded as indicated by a decrease in liver triglyceride content (40%). The activities of glycerophosphate acyltransferase, acyl-CoA: 1,2-diacylglycerol acyltransferase and CTP:phosphocholine cytidylyltransferase were increased. The cholesterol lowering effect was accompanied by a reduction in HMG-CoA reductase activity (80%) and acyl-CoA:cholesterol acyltransferase activity (33%). In hepatocytes treated with methyl 3-thiaoctadeca-6,9,12,15-tetraenoate, fatty acid oxidation was increased 1.8-fold compared to controls. The results suggest that treatment with methyl 3-thiaoctadeca-6,9,12,15-tetraenoate reduces plasma triglycerides by a decrease in the availability of fatty acid substrate for triglyceride biosynthesis via enhanced fatty acid oxidation, most likely attributed to the mitochondrial fatty acid oxidation. It is hypothesized that decreased phosphatidate phosphohydrolase activity may be an additive mechanism which contribute whereby 3-thia fatty acids reduce triglyceride formation in the liver. The cholesterol-lowering effect of the polyunsaturated 3-thia fatty acid ester may be due to changes in cholesterol/cholesterol ester synthesis as 60% of this acid was observed in the hepatic cholesterol ester fraction.

Strategies of Homeothermy in Eider Ducklings (Somateria Mollissima)

While most nest-dwelling birds depend on parental brooding to maintain normal body temperature(TB) during the first days of life (Riclefs, 1974), nest-fleers appear to rely on endogenous heat (Koskimies and Lahti,1964). We have studied eider ducklings breeding near the Research Station of The Norwegian Polar Institute at Ny Alesund, Svalbard (79° 55′). The young eiders leave the nest once they have dried at the age of 6–8 hours and from then on spend most of their time on the ice-strewn water.