Sustained zero-order delivery of GC-1 from a nanochannel membrane device alleviates metabolic syndrome.

BACKGROUND/OBJECTIVES: Our objective was to assess the sustained, low-dose and constant administration of the thyroid receptor-ß (TRß)-selective agonist GC-1 (sobetirome) from a novel nanochannel membrane device (NMD) for drug delivery. As it known to speed up metabolism, accomplish weight loss, improve cholesterol levels and possess anti-diabetic effects, GC-1 was steadily administered by our NMD, consisting of an implantable nanochannel membrane, as an alternative to conventional daily administration, which is subject to compliance issues in clinical settings. SUBJECTS/METHODS: Diet-induced obese C57BL/J6 male mice were fed a very high-fat diet (VHFD) and received NMD implants subcutaneously. Ten mice per group received capsules containing GC-1 or phosphate-buffered saline (control). Weight, lean and fat mass, as well as cholesterol, triglycerides, insulin and glucose, were monitored for 24 days. After treatment, plasma levels of thyroid-stimulating hormone (TSH) and thyroxine were compared. mRNA levels of a panel of thermogenic markers were examined using real-time PCR in white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose tissue, liver and local inflammatory response to the implant were examined histologically. Pancreatic islet number and ß-cell area were assessed. RESULTS: GC-1 released from the NMD reversed VHFD-induced obesity and normalized serum cholesterol and glycemia. Significant reductions in body weight and fat mass were observed within 10 days, whereas reductions in serum cholesterol and glucose levels were seen within 7 days. The significant decrease in TSH was consistent with TRß selectivity for GC-1. Levels of transcript for Ucp1 and thermogenic genes PGC1a, Cidea, Dio2 and Cox5a showed significant upregulation in WAT in NMD-GC-1-treated mice, but decreased in BAT. Although mice treated by NMD-GC-1 showed a similar number of pancreatic islets, they exhibited significant increase in ß-cell area. CONCLUSIONS: Our data demonstrate that the NMD implant achieves steady administration of GC-1, offering an effective and tightly controlled molecular delivery system for treatment of obesity and metabolic disease, thereby addressing compliance.

Comparative antioxidant activity of tocotrienols and other natural lipid-soluble antioxidants in a homogeneous system, and in rat and human lipoproteins.

The antioxidant activity of tocotrienols toward peroxyl radicals was compared with that of other natural lipid-soluble antioxidants in three different systems by measuring the temporal disappearance of antioxidants and the formation of lipid hydroperoxides. In homogeneous solution, the initial rates of consumption of the various antioxidants, assessed by competition experiments between pairs of antioxidants for radicals, decreased in the order: ubiquinol-10 approximately ubiquinol-9 > alpha-tocopherol approximately alpha-tocotrienol > beta-carotene approximately lycopene > gamma-tocopherol approximately gamma-tocotrienol. Following in vitro incubation of human plasma with alpha-tocotrienol, this form of vitamin E was present in all classes of lipoproteins isolated from the supplemented plasma. Dietary supplementation of rats and humans with a tocotrienol-rich preparation resulted in a dose-dependent appearance of alpha- and gamma-tocotrienols in plasma and all circulating lipoproteins, respectively. Exposure of such enriched rat plasma to aqueous peroxyl radicals resulted in simultaneous consumption of the alpha- and then gamma-isomers of vitamin E. The sequence of radical-induced consumption of antioxidants in freshly isolated, in vitro and in vivo tocotrienol-enriched low density lipoprotein (LDL) was again ubiquinol-10 > alpha-tocotrienol approximately alpha-tocopherol > carotenoids > gamma-tocopherol approximately gamma-tocotrienol. Under conditions where radicals were generated at constant rates, the rate of lipid hydroperoxide formation in LDL was not constant. It proceeded in at least three stages separated by the phase of ubiquinol-10 consumption and, subsequently, that of alpha-tocopherol/alpha-tocotrienol. Our results show that dietary tocotrienols become incorporated into circulating human lipoproteins where they react with peroxyl radicals as efficiently as the corresponding tocopherol isomers.

Effect of feeding protected lipids on fatty acid synthesis in ovine tissues.

The effects of including protected lipid supplements in the sheep diet have been studied by measuring the incorporation of [1-14C]acetate into tissue fatty acids in vivo and in vitro. Supplementing the diet with protected lipid significantly (P > 0.05) depressed lipogenesis in adipose tissue both in vovo and in vitro. However, when protected lipids of different fatty acid composition were given to lambs, the protected safflower oil supplement containing high levels of linoleic acid was the only treatment to cause a significant (P > 0.05) depression in fatty acid synthesis in adipose tissue, the major site of lipogenesis in the sheep. Larger adipose cells in the lipid-supplemented sheep indicate that these sheep were fatter than those receiving the basal diet. Therefore, supplemented wethers deposited more fat than sheep receiving the basal diet and this fat was derived from the supplement rather than from de novo synthesis.

Sire effect on fatty acid composition of ovine adipose tissue.

The fatty acid composition of perirenal adipose tissue from 255 purebred and crossbred sheep was examined to determine the genetic effects of sire on each of five fatty acids. The sheep, all rams, were the progeny of 30 Dorset Horn sires. The animals were grazed on pasture and slaughtered at an average age of 21 months, when their mean carcass weight was 30 kilograms. The fatty acids studied and their mean percentage compositions were: stearic, 38%; oleic, 31%; palmitic, 20%; palmitoleic, 2%, and linoleic, 2%. These amounted to over 90% by weight of the tissue sample fatty acids. In addition, numerical functions were constructed as ratios for two pairs of fatty acids, ratio 1 (palmitoleic to palmitic) and ratio 2 (oleic to stearic), for estimation of the desaturase enzyme activity in the tissue samples studied. A Softness Index, expressed as a ratio between monounsaturated and saturated acids, was also included in the analysis. Significant birth year and maternal breed effects were found for all the traits studied. This was in contrast to the regression on slaughter age, which with two exceptions was not a significant source of variation in the data. The sire effect, based on 27 degrees of freedom, was highly significant or significant for all traits except stearic or linoleic acid and ratio 2. These results are discussed with reference to utilization of genetic variation between sites in selective breeding programs to modify fatty acid composition of ovine adipose tissue.

Colchicine poisoning.

Colchicine poisoning is an unusual but serious form of drug intoxication. Although relatively uncommon, colchicine poisoning may produce life-threatening systemic effects that must be recognized and treated by the emergency physician. This alkaloid found in Colchicum autumnale is used primarily in the treatment of gout. In toxic doses it produces nausea and vomiting, and bone marrow suppression often leading to sepsis, hypocalcemia, adult respiratory distress syndrome, and direct cardiotoxic effects. Treatment requires early recognition and supportive care including fluid and electrolyte replacement and occasionally blood component replacement therapy. Recent experiments using colchicine-specific antibodies have demonstrated beneficial effects on colchicine intoxication.

Research note: effects of dietary fats on hepatic cholesterol synthesis in Japanese quail.

Blood lipid concentrations and hepatic cholesterol synthesis were compared in Japanese quail fed diets containing fats with different fatty acid profiles. The quail fed a diet containing tuna oil had the lowest blood cholesterol concentration; those fed beef drippings the highest, and those fed safflower oil or linseed oil had intermediate concentrations. Rates of hepatic cholesterol synthesis mirrored the results for serum cholesterol concentration. Serum triglyceride concentrations were lower in the quail fed the two diets containing n-3 fatty acids in comparison with the beef and safflower treatment groups.

Effect of diet and substrate on the in vitro measurement of cholesterol and fatty-acid synthesis in hepatic tissue of Japanese quail.

A comparison of acetate, glucose, mevalonate, or water as radioactive substrates for the hepatic synthesis of cholesterol, fatty acids, and glyceride-glycerol was made in Japanese quail fed diets containing either beef fat or tuna oil. The quail fed a diet containing beef fat were fatter and had a significantly higher (P less than .01) concentration of serum cholesterol (5.6 mM per L) than that measured in the serum of quail given tuna oil (4.1 mM per L). Both in vitro cholesterol and fatty-acid synthesis were greater in the quail fed a diet of beef fat than in those fed a diet containing tuna oil. The results showed that mevalonate was the most-suitable radioactive substrate for measuring cholesterol synthesis, whereas glucose was the most-suitable radioactive substrate for measuring fatty-acid and glyceride-glycerol synthesis.

The cellular basis for growth of the abdominal fat pad in broiler-type chickens.

Cellular growth of the abdominal fat pads from Tegel TM70 white broiler chickens was characterized by both hyperplasia and hypertrophy of adipose cells until the chickens were approximately 14 weeks old, after which hypertrophy of existing adipose cells was solely responsible for increases in the mass of these fat deposits. The percent body fat was linearly and positively correlated with the weight of abdominal fat. However, at a constant percent body fat, male birds had a larger deposit of fat in the abdominal region than did females. Thus, a different relationship to predict body fat would be required for each sex. In mature birds the mass of an adipose tissue deposit is generally reflected in the size of adipose cells rather than the number of cells in an adipose organ.

The effect of dietary monoterpenes on the cholesterol level of eggs.

Monoterpenes were included in the diets of laying hens in an attempt to inhibit the synthesis of cholesterol and hence reduce its amount in egg yolk. However, feeding five monoterpenes, phorone or 200 mg. cholesterol per day to hens did not significantly change the level of cholesterol in the egg yolk. These compounds did not cause signs of ill health in the hen or a decline in egg production.

Relationships among growth, adipose cell size, and lipid metabolism in ruminant adipose tissue.

In early postnatal development, growth of adipose tissue is due to both cellular hypertrophy and hyperplasia. Adipose cell (adipocyte) hypertrophy is the major mechanism in fattening of ruminants grown to market weight, although evidence is accumulating that preadipose cells can proliferate postnatally, even in mature animals. In interfasicular adipose tissue (marbling), however, small adipose cells are present and their number makes a positive contribution to the size of this fat depot in ruminants of market weight. Present information does not indicate whether these small cells are newly synthesized cells or are cells that differentiated early in postnatal development and fill with lipid at some later time. Limitations on detecting small adipose cells in cell-counting techniques are partly responsible for conflicting conclusions on the cellular basis for adiposity. Nutritional modification of adipose cell number has been reported in rodents. However, the extreme nutritional modifications required to alter cell number have little practical application in the growth of ruminants for meat production. Adipose cells of various sizes respond differently in the esterification and synthesis of fatty acids. The greater rates of lipid synthesis from acetate in large adipose cells may be related to increased uptake of substrate in cells with a large surface area.

Distribution of milk fat globules in cow's milk high in linoleic acid.

The influence of feeding cows formaldehyde-treated polyunsaturated oilseed supplement on fatty acid composition and distribution of particle size of milk fat globules has been studied. Supplement increased linoleic acid in milk fat from 1.7 to 27.4%. Distributions of particle size measured by a Coulter counter showed that milk fat from cows receiving supplement had large milk fat globules than those in milk fat of the same cows when supplementation was discontinued. However. this difference in size could not be attributed to percent linoleic acid in the milk fat since correction of the data of supplemented cows for percent milk fat and size of milk fat globules resulted in particle distributions strikingly similar in shape.

Cellularity of bovine adipose tissue.

Subcutaneous and perirenal adipose tissue from bovine animals that had different fat deposition patterns were characterized in terms of the weight of the adipose tissue organ and adipose cell number and mean cell size as determined by electronic counting of osmium-fixed adipose cells. Similar parameters were also measured in the interfascicular adipose tissue dissected from four muscles. Adipose tissue from animals of the leaner Holstein breed contained smaller cells than the respective tissues from the fatter Hereford x Angus animals. The small subcutaneous deposit in the Holstein animals was due to a small number of adipose cells that were small in size. During growth of the bovine animal, an increase in adipose tissue mass was accompanied by cellular hypertrophy and hyperplasia. However, by 14 months of life hyperplasia was complete in all but the interfascicular adipose tissue. In the 14-month-old Hereford x Angus steers, interfascicular adipose tissue had an appreciable number of small cells and a bimodal distribution for cell diameter. The results of this study suggest that interfascicular adipose tissue is a late developing depot and that hyperplasia is still an active process in this depot at 14 months of life, whereas hyperplasia appears to be nearly complete in the subcutaneous and perirenal depots of bovine animals by about 8 months of life or shortly thereafter. Correlation coefficients indicated that intramuscular lipid content was positively related to the number of interfascicular adipose cells per 100 g of muscle in four different muscles. However, average cell diameter and volume were significantly correlated to intramuscular lipid content in only one of the four muscles studied.

Cellularity of porcine adipose tissue: effects of growth and adiposity.

Adipose tissue, from two depots in pigs of three breeding groups with different propensities to fatten, was characterized in terms of weight of the adipose tissue organ, adipose cell number, and mean cell volume as determined by electronic counting of adipose cells fixed with osmium tetroxide. Perirenal and extramuscular adipose tissue growth was accompanied by progressive adipose cell enlargement along with an increase in cell number. By approximately 18-20 weeks of life, adipose tissue growth in both lean Hampshire x Yorkshire and fat Minnesota 3 x 1 pigs occurred exclusively by cellular hypertrophy. By 24 weeks of life (37 kg), hyperplasia was complete in Hormel Miniature pigs, which contained about one-third as many extramuscular adipose cells as the conventional pigs. Adiposity in the pig was due to cellular hypertrophy rather than cellular hyperplasia, since during growth, the leaner conventional pigs (30.6% extramuscular fat) contained more adipose cells than the fatter pigs (46.6% extramuscular fat). The number of adipose cells per animal or per adipose organ was directly related to the true body size (weight of fat-free carcass) of the animal. Fat Minnesota 3 x 1 pigs had fewer adipose cells than lean Hampshire x Yorkshire pigs at an equivalent live weight due to the smaller true body size of these animals. In young animals (28 and 54 kg), growth rate was positively correlated with adipose cell number. However, growth rate was unrelated to the total number of cells in the more mature animals (83 and 109 kg). Therefore a slow, normal growth rate may delay but not alter the final cell number.

A technique to study the relationship between adipose cell size and lipogenesis in a heterogeneous population of adipose cells.

A technique is described for the calculation of the incorporation of radioactive substrate into lipid in adipose cells that have been isolated and separated into groups according to their diameter from a single sample of adipose tissue containing a heterogeneous population of cells. After incorporation of radioactive substrate, a section of adipose tissue is fixed in osmium tetroxide and the fixed cells isolated and separated into specific diameter ranges using a series of nylon screens. The separated cells are weighed, decolorized with hydrogen peroxide, and the radioactivity is determined in the cells from each diameter range. With this method, true comparisons can be made between adipose cell size and lipogenic activity of isolated cells of known diameter which have been subjected to various nutritional or hormonal treatments. Results with sheep adipose tissue show that large adipose cells are considerably more active in the synthesis of lipid than small cells from the same sample of adipose tissue.

Biotin and the sudden infant death syndrome.

A diet which is marginally deficient in the vitamin biotin may cause sudden unexpected death of young broiler chickens when they are exposed to stress. Chickens affected with this disorder have low levels of biotin in their livers. In conditions of biotin insufficiency, we postulate that a similar disorder, triggered by mild stress, may occur in the human infant. We have now used a radiochemical technique to measure the biotin content of 204 livers obtained from infants at autopsy. The levels of biotin in the livers of infants who had died of sudden infant death syndrom (SIDS; cot death) were significantly lower than those in livers of infants of similar age, who had died of explicable causes. These findings support an association of biotin with SIDS.

Induction of vitellogenin in primary monolayer cultures of cockerel hepatocytes.

A primary monolayer culture system from cockerel hepatocytes was established. The cultures synthesize and secrete proteins that comigrate with authentic serum proteins on polyacrylamide gels and are found in the same relative abundance. Addition of estradiol increased the synthesis of apoprotein B, found in very low density lipoprotein, under all culture conditions. Vitellogenin synthesis could not be induced directly by estradiol. However, when serum was obtained from cockerels injected with estradiol 4 days before blood collection and included in the culture medium, the cultures secreted a protein identified immunologically as vitellogenin by affinity chromatography. Furthermore, addition of growth hormone or prolactin to cultured cockerel hepatocyte monolayers resulted in the synthesis and secretion of a polypeptide that comigrates with authentic vitellogenin on polyacrylamide gels.

Inhibition by potential metabolic inhibitors of in vitro adipose tissue lipogenesis.

To study the pathway of lactate utilization as a carbon source for fatty acid synthesis, the effect of (-)-hydroxycitrate, agaric acid, sodium oxamate, 2-n-butyl malonate and alpha-cyano-4-hydroxycinnamate on the rate of in vitro conversion of lactate, acetate and glucose to fatty acids was measured in bovine and rat adipose tissues. Sodium oxamate and hydroxycitrate caused less fatty acid to be synthesized from lactate in bovine adipose tissue. Hydroxycitrate depressed fatty acid synthesis from glucose in rat adipose tissue. alpha-Cyano-4-hydroxycinnamate was an effective inhibitor of lipogenesis from all substrates and may act as a specific inhibitor in adipose tissue. Although the inhibitors were absorbed poorly into adipocytes, the results indicate that conversion of lactate to fatty acids probably occurs by way of the citrate cleavage pathway.