Beta-oxidation of medium chain (C8-C14) fatty acids studied in isolated liver cells

The beta-oxidation and esterification of medium-chain fatty acids were studied in hepatocytes from fasted, fed and fructose-refed rats. The beta-oxidation of lauric acid (12:0) was less inhibited by fructose refeeding and by (+)-decanoyl-carnitine than the oxidation of oleic acid was, suggesting a peroxisomal beta-oxidation of lauric acid. Little lauric acid was esterified in triacylglycerol fraction, except at high substrate concentrations or in the fructose-refed state. With [1-14C]myristic acid (14:0), [1-14C]lauric acid (12:0), [1-14C]octanoic acid (8:0) and [2-14C]adrenic acid (22:4(n - 6] as substrate for hepatocytes from carbohydrate-refed rats, a large fraction of the 14C-labelled esterified fatty acids consisted of newly synthesized palmitic acid (16:0), stearic acid (18:0) and oleic acid (18:1) while intact [1-14C]oleic acid substrate was esterified directly. With [9,10-3H]myristic acid as the substrate, small amounts of shortened 3H-labelled beta-oxidation intermediates were found. With [U-14C]palmitic acid, no shortened fatty acids were detected. It was concluded that when the mitochondrial fatty acid oxidation is down-regulated such as in the carbohydrate-refed state, medium-chain fatty acids can partly be retailored to long-chain fatty acids by peroxisomal beta-oxidation followed by synthesis of C16 and C16 fatty acids which can then stored as triacylglycerol.     

Effects of tetrahydrolipstatin, a lipase inhibitor, on absorption of fat from the intestine of the rat

Tetrahydrolipstatin (THL) derived by hydrogenation from lipstatin, a lipase inhibitor produced by Streptomyces toxytricini, has been shown to inhibit in vitro the activity of all three lipases secreted to the gastro-intestinal tract; gastric lipase, pancreatic lipase and carboxylester lipase (cholesterol ester hydrolase). The effects of THL on intestinal absorption of fat (transport to the thoracic duct chyle) has now been investigated after intraduodenal infusion in a rat model. Absorption of label from oleic acid when administered with monoolein in micellar bile salt solution was not affected by THL in concentrations up to 10(-4) M calculated on the volume of the aqueous phase. Absorption of free cholesterol in micellar bile salt solution of the lipolytic products of triolein; oleic acid and monoolein, is not significantly affected at a concentration of THL of 10(-4) M. Absorption of cholesterol from cholesteryl oleate under the same conditions is almost completely inhibited. The results indicate that absorption of free cholesterol is not dependent on the activity of pancreatic cholesterol ester hydrolase. The absorption of emulsified triolein was not significantly affected by 10(-5) M THL but decreased to around 30% of the controls by a concentration 10-times higher. There was no significant decrease of cholesterol absorption when administered in emulsified triolein while absorption of cholesteryl oleate was reduced at both concentrations of THL and almost completely at 10(-4) M. Radioactivity from [2-14C]THL when administered emulsified in triolein was recovered in urine, bile and thoracic duct lymph to 10-14, 8-13 and 1-3%, respectively, largely independent on dose administered. Label from [1"-14C] THL was recovered in the same amounts in lymph but much less in bile and urine indicating that the amino acid moiety has been split off early in the absorption process.     

Sulphation causes heterogeneity of gastric mucins

The synthesis of mucus glycoprotein in rat stomach was studied in stomach segments, which were pulse-labelled with both [3H]galactose and [35S]sulphate and chased for various times. The radioactive glycoproteins were analyzed by CsCl centrifugation and by agarose gel electrophoresis. After a pulse-labelling for 15 min with [3H]galactose, a possible intermediate with an Mr of 200,000 and a buoyant density of 1.60 g/ml could be demonstrated. Following chase periods of 1 and 4 h, [3H]galactose and [35S]sulphate were present in glycoproteins with a mean buoyant density of 1.50 g/ml. This is clearly different from the main density of glycoproteins isolated from mucosal scrapings (1.46 g/ml). Another difference is the high electrophoretic mobility on gel electrophoretic analysis of newly synthesized glycoproteins compared to that of the major portion of the glycoproteins from mucosal scrapings. When sulphation of glycoproteins was inhibited by sodium chlorate, electrophoretic mobility and buoyant density both decreased. Sodium chlorate had no effect on glycoprotein synthesis nor on glycoprotein secretion. We conclude from our data that the heterogeneity in electrophoretic mobility and buoyant density can be attributed to a different degree of sulphation of the same glycoprotein.     

Genetico-demographic patterns of the prevalence of various forms of endogenous psychoses

Prevalence rates (PRs) for EFP (schizophrenic, schizoaffective and affective psychoses), with allowance for proband sex and age-of-onset data were studied in a subdivided population from the North-East of the European Region of the USSR. The population includes three subpopulations: a small old religious semi-isolate of Russians ("Rs"), aboriginal Komi people ("Ks")--an ethnic community of Ugro-Finnish lineage, and a mixed group of migrants ("Ms") from various regions of the USSR. The latter is mainly an urban population, while the "Rs" and "Ks" are, on the whole, rural populations. The total PR for EFP was found to be 0.97% for the "Rs", 0.63% for the "Ks" and 0.35% for the "Ms", whereas PRs-0.85-1.15% in other parts of the USSR, mainly for "panmixed" populations in large towns. The lower PRs for EFP in the "Ms" is caused by a backmigration flow involving certain groups of patients; consequently, the mean liability for "Ms" offsprings (as a whole) should also be lower. On the other hand, the lower PRs for EFP in the "Ks" is caused by underpresentation of clinically mild cases of the mental disease (mainly, pseudoneurotic schizophrenia), especially among female patients, probably due to that the so affected persons are sufficiently adapted to the cultural traditions of this rural population. It was shown that in the "Rs" the total PR for "nuclear" and paranoid schizophrenia is 0.68% versus 0.25% in a "panmixed" population. The increase is most likely caused by the high inbreeding level in the "Rs" semi-isolate, and if this is correct, we may suppose that at least one or two recessive genes are involved in the liability to the most heavy forms of schizophrenia. On the other hand, in the "Ms" (as in other "panmixed" populations) positive assortative mating among hereditary-predisposed persons is a more significant factor influencing family transmission of EFP, since the correlation between probands and their spouses is rpp = 0.31 (p less than 0.001) in the "Ms", as compared to rpp = 0.19 (p less than 0.1) in the "Rs". Thus, our general conclusion is that neither the place of inhabitance nor the life mode are the causal factors for EFP, but rather some genetic factors, more accurately, certain sets of specific genes.     

Expression of vimentin and glial fibrillary acidic protein in human developing spinal cord

Summary Expression of intermediate filament proteins was studied in human developing spinal cord using immunoperoxidase and double-label immunofluorescence methods with monoclonal antibodies to vimentin and glial fibrillary acidic protein (GFAP). Vimentin was found in the processes of radial glial cells in 6-week embryos, while GFAP appeared in vimentin-positive astroglial cells at 8–10 weeks. GFAP and vimentin were present in approximately equal amounts in differentiating astrocytes in 23-week spinal cord. In 30-week fetuses, astrocytes reacted strongly for GFAP, while both the reaction intensity and the number of vimentin-positive cells fluctuated predominantly in the grey matter. No clear-cut transition from vimentin to GFAP was noticed during the development of astrocytes. The majority of ependymal cells in 23-week fetuses contained vimentin but only a few of them reacted for GFAP. The expression of vimentin continued during the whole development of the ependymal layer, in contrast to the reactivity for GFAP which disappeared between the 30th week and term.     

Aggregation of littoral macrobenthic species: some theoretical and practical considerations

The spatial pattern of macrozoobenthos in an intertidal area was studied. Four commonly used measures of aggregation, the V/m ratio, k of the negative binomial distribution, the indices of Lloyd and b of the Taylor power function, were calculated and compared for 13 species based on 176 samples. It is argued that, contrary to common practice, the b value of the Taylor power function should not be used without the value of a, since it only measures how aggregation changes with density. The parameter k of the NBD is found to be an unreliable index of aggregation and the indices of Lloyd are difficult to interpret as well. There is very good agreement between the results of the V/m ratio and the b value of the Taylor power function. Only three species are distributed randomly, all others being aggregated. The consequences on the accuracy of sampling is discussed and it is concluded that 5 samples of 176 cm² give an accuracy of 50% for the common species.     

Seasonal variations in the loosely sorbed phosphorus fraction of the sediment of a shallow and hypereutrophic lake

Material cycling

Seasonal variations in the loosely sorbed phosphorus fraction of the sediment of a shallow and hypereutrophic lake     

Stimulation of inositol phospholipid breakdown in pig brain miniprisms by carbachol and monoamines: effect of K+

1. The effects of carbachol, monoamines and K+ upon the rate of inositol phospholipid breakdown in pig brain miniprisms have been investigated. 2. In the striatum, carbachol (EC50 approx. 1 microM) and noradrenaline (EC50 approx. 25 microM) stimulated inositol phospholipid breakdown, whereas 5-hydroxytryptamine (1-1000 microM) was without effect. 3. The rate of inositol phospholipid breakdown was increased by raising the assay [K+] to greater than or equal to 40 mM. In the hippocampus and hypothalamus, a synergistic effect between K+ and carbachol was noted, whereas in the striatum, the effects were additive. 4. In striatal and hippocampal miniprisms, dopamine also increased inositol phospholipid breakdown, albeit only at high (greater than or equal to 1 mM) concentrations. Dopamine (1 mM) reduced the stimulation produced by noradrenaline (1 mM), suggesting that the effect of dopamine is due to a weak noradrenergic action of this catecholamine.     

The epsilon-subunit of ATP synthase from bovine heart mitochondria. Complementary DNA sequence, expression in bovine tissues and evidence of homologous sequences in man and rat.

The epsilon-subunit of ATP synthase from bovine heart mitochondria is assembled into the extrinsic membrane sector, F1-ATPase. The mature protein is 50 amino acid residues in length and its function is unknown. It is a nuclear gene product that is imported into the organelle. A mixture of 64 oligonucleotides 17 bases long, designed on the basis of the known protein sequence, was synthesized and used as a hybridization probe to isolate a cognate cDNA clone from a bovine library. The DNA sequence of this clone was determined, and the protein sequence of the epsilon-subunit deduced from it agrees exactly with that determined by direct sequence analysis of the protein isolated from bovine hearts. The bovine cDNA was used as a hybridization probe to examine the expression of the epsilon-subunit in various bovine tissues. mRNAs related to the cDNA are found in all of these tissues, and no evidence was obtained of the presence of mRNAs for the epsilon-subunit with similar coding sequences and dissimilar 3' non-coding regions. By hybridization experiments with digests of DNA from cow, man and rat it has been shown that sequences related to the bovine cDNA are present in the genomes of all three species. More than one related sequence was detected in all cases, indicating the presence in all three genomes of more than one gene and/or pseudogenes.     

Poly(A) tail shortening is the translation-dependent step in c-myc mRNA degradation.

The highly unstable c-myc mRNA has been shown to be stabilized in cells treated with protein synthesis inhibitors. We have studied this phenomenon in an effort to gain more insight into the degradation pathway of this mRNA. Our results indicate that the stabilization of c-myc mRNA in the absence of translation can be fully explained by the inhibition of translation-dependent poly(A) tail shortening. This view is based on the following observations. First, the normally rapid shortening of the c-myc poly(A) tail was slowed down by a translation block. Second, c-myc messengers which carry a short poly(A) tail, as a result of prolonged actinomycin D or 3'-deoxyadenosine treatment, were not stabilized by the inhibition of translation. We propose that c-myc mRNA degradation proceeds in at least two steps. The first step is the shortening of long poly(A) tails. This step requires ongoing translation and thus is responsible for the delay in mRNA degradation observed in the presence of protein synthesis inhibitors. The second step involves rapid degradation of the body of the mRNA, possibly preceded by the removal of the short remainder of the poly(A) tail. This last step is independent of translation.