Elevated Lipid Content Research Articles

Modulation of luteal activity in postpartum beef cows through changes in dietary lipid.

Studies were conducted to evaluate the normal changes in lipid metabolism occurring in the suckled Brahman crossbred female during the postpartum period (Exp. 1) and to examine the function of induced corpora lutea (CL) in postpartum cows fed diets with normal (2.8%) lipid or elevated (8%) lipid content (Exp. 2). Multiparous and primiparous females (n = 20), maintained on pasture without energy or protein supplementation, were used in Exp. 1. A linear increase (P less than .001) in plasma lipid metabolites was observed between the 1st and 8th wk after calving, reaching a plateau of 221 +/- 18.3 and 74 +/- 3.4 mg/dl for total cholesterol and triglycerides, respectively. Seventy percent of all postpartum females exhibited luteal activity within 50 d (x = 34.7 d), and 59% of these animals exhibited short luteal phases (less than 12 d). In Exp. 2, primiparous and multiparous females (n = 32) were assigned to receive a control (n = 16) or high-lipid (HL) diet (n = 16; 30% whole cottonseed) between d 1 and d 38 after calving. The HL diet increased (P less than .001) total cholesterol and triglycerides 1.7- and 1.4-fold, respectively, relative to controls, and increased (P less than .05) the spontaneous occurrence of low-level progesterone elevations. Forty-eight-hour calf removal and gonadotropin-releasing hormone (GnRH; .22 mg/kg BW i.v.) were employed between d 21 and 26 after calving to induce ovulations. Mean concentrations of progesterone in the HL group were markedly higher (P less than .01) than in controls between d 5 and 8 of the induced cycle, and average lifespan of induced CL was approximately twice that of controls (P less than .01).

PHYSIOLOGICAL CHARACTERIZATION OF SIX LIPID‐PRODUCING DIATOMS FROM THE SOUTHEASTERN UNITED STATES1

ABSTRACTSix strains of diatoms from intertidal waters were isolated as part of the SERI Aquatic Species Program collection and screening effort: Amphiprora hyalina Greville, Cyclotella cryptica Reimann, Lewin & Guillard, Navicula acceptata Hustedt (two strains, NAVIC6 and NAVIC8), Navicula saprophila Lange‐Bertalot & Bonik, and Nitzschia dissipata (Kütz.) Grunow. Among numerous algal strains isolated as part of this collection effort, these six strains showed rapid growth and elevated lipid content in preliminary screening experiments and were chosen for further physiological characterization. N. dissipata grew most rapidly at 25°C, whereas the other five strains grew best at 30–35°C. Salinity tolerance varied among strains, with maximal growth occurring at the following conductivities: 10–60 mS.cm−1 (A. hyalina and N. acceptata NAVIC8), 10–35 mS.cm−1 (C. cryptica), 20–45 mS.cm−1 (N. acceptata NAVIC6), 10 mS.cm−1 (N. saprophila), and 20–35 mS.cm−1 (N. dissipata). The diatoms also differed in their utilization of nitrogen sources with A. hyalina growing optimally with either nitrate or urea; N. acceptata NAVIC6, with either nitrate or ammonium; C. cryptica, N. acceptata NAVIC8, and N. dissipata, with nitrate; and N. saprophila, with urea. Under optimal conditions, A. hyalina grew at 2.0 doublings. day−1; C. cryptica grew at 3.0 doublings. day−1. Each Navicula strain had a growth rate of 3.8 doublings. day−1, and N. dissipata grew at 2.6 doublings.day−1. All six strains had lipid contents in excess of 37% ashfree dry weight (AFDW) under nutrient‐limited conditions, with N. saprophila having the highest lipid content at 48% AFDW.

Interaction between ovine growth hormone and triiodo-L-thyronine on metabolic reserves of rainbow trout,Salmo gairdneri

Rainbow trout (Salmo gairneri) were given slow-release coconut oil implants which contained triiodo-L-thyronine (T3) and were subsequently administered ovine growth hormone (oGH) (either 0.24 or 2.5 μg/g body weight) or saline every seventh day for four injections. The purpose of the study was to examine the interactions between oGH and T3 on several aspects of the metabolism in rainbow trout.Trout treated with T3 alone had higher carcass water content, lower liver glycogen, higher plasma T3 levels and lower plasma cholesterol, triglyceride and protein levels compared with the controls implanted with coconut oil implants alone. Trout treated with oGH alone had higher condition factors, lowered carcass total lipid content, elevated liver lipid and RNA content, and elevated plasma T3 and L-thyroxine (T4) levels compared with the coconut oil-implanted and saline-injected controls. Trout treated with T3 and oGH had lower liver glycogen content, higher plasma T3 and fatty acid levels and lower plasma T4, cholesterol and triglyceride levels compared with the controls given coconut oil implants and saline injections alone. There were no apparent effects of either hormone alone or in combination on liver: body mass ratios, liver DNA content, liver RNA:DNA ratios, liver RNA:protein ratios, liver protein:DNA ratios and liver protein content.The data suggest an interaction between oGH and T3 as regards the regulation of condition factor, carcass water content, carcass and liver total lipid content, liver RNA content, plasma fatty acid and plasma protein content.

The effect of vitamin D deficiency on rat bone lipid composition

Vitamin D and phosphate deficiency has been shown previously to result in an accumulation of calcium acidic phospholipid phosphate complexes in the epiphysis of immature rats and to increase the cholesterol and decrease the lysophosphatide content throughout bone. To define the effects of vitamin D deficiency and those of combined vitamin D and phosphate deficiency, the lipid composition of the bones of second generation rachitic rats, raised on a diet that was vitamin D deficient was compared to that of normal animals fed a vitamin D-repleted diet and to previously studied vitamin D and phosphate-deficient rats. Animals raised on the vitamin D-deficient diet in utero and during postfetal life were serologically quite different from controls. These animals were significantly hypocalcemic and had no detectable vitamin D metabolites. Similar to the previously studied phosphate-deficient rachitic animals, the vitamin D-deficient animals had significantly elevated total lipid contents (weight percent lipid per demineralized dry weight) throughout their bones as compared to controls (epimetaphysis 9.6 vs 6.7 ( P ≤ 0.03), diaphysis 6 vs 2 ( P ≤ 0.01), calvaria 6.1 vs 2.4 ( P ≤ 0.002). Similar to the vitamin D and phosphate-deficient animals, the second generation vitamin D-deficient rat bones had elevated cholesterol and reduced lysophosphatide contents. Complexed acidic phospholipids were not significantly elevated in the vitamin D-deficient animal bones. The data suggest that the lipid changes seen in these animals are due to vitamin D deficiency and not to phosphate deficiency. The presence of comparable levels of complexed acidic phospholipids in bones formed by different osteogenic pathways indicates the similarity of mineralization mechanisms in these tissues.

Changes in lipids during matrix: induced endochondral bone formation.

The changes in lipids occurring during the process of endochondral ossification have been characterized by studying the discrete phases of matrix-induced endochondral bone formation in the rat. Calcium-acidic phospholipid-phosphate complexes were shown to increase in concentration during cartilage calcification (day 9) and to peak in content during early bone formation (days 11-13), the times during which the rate of mineral deposition, as indicated by the change in ash weight was greatest. These data support the hypothesis that the calcium-acidic phospholipid-phosphate complexes play a role in the in vivo initiation of hydroxyapatite deposition. The overall lipid composition of the induced matrix newly formed cartilage (days 7-9) was comparable to that of normal cartilage, with the phospholipid composition matching that of chondrocyte plasma membranes. Times of vascular invasion and formation of marrow cavities were marked by elevated total lipid and triglyceride contents.

Toxicology of brominated fatty acids: metabolite concentration and heart and liver changes.

Rats were fed for 35 days diets containing 2% of either brominated corn oil (BCO), monoglyceride of dibromostearate (DBS), monoglyceride of tetrabromostearate (TBS) or a mixture of the two monoglycerides (BMG) which provided proportions of brominated acids comparable to that of the BCO. Hearts from all animals fed BCO were yellow colored and firm in texture. Myocardial cellular degeneration, mild to moderate edema and occasional small necrotic foci were observed. Hearts from animals fed DBS showed moderate edema and some slight necrosis. All diets produced an increase in lipid content of heart. Animals fed the experimental diets developed enlarged livers and showed elevated liver lipid content. The tetrabromostearate appeared to be the more active in producing these changes, in particular a severe intracellular fatty degeneration. Shorter-chain (C-16, C-14) metabolites of di- and tetrabromostearate were identified and the concentration of brominated fatty acids in heart, liver and adipose tissue determined and found to account for 80% of the bromine detected in these tissues by neutron activation analysis. TBS accumulated in liver while the highest concentration of DBS was observed in heart lipids. Although the concentrations of brominated acids in heart and liver lipids were comparable in rats fed BCO or BMG, BCO produced the more pronounced effects. This differential could be due to additional active components in BCO or to a variation in response associated with changes in the location of the fatty acid on the glycerol molecule.

Reversibility of the effects of the host immune response on the intestinal phase of Trichinella spiralis in the mouse, following transplantation to a new host.

On day 10 of a primary infection of Trichinella spiralis in NIH mice, when adult worms were in the process of being expelled, their fecundity was markedly depressed. Upon transplantation to new host mice, the worms were able to establish successfully in their usual position in the anterior small intestine, even if originally recovered from the large intestine of mice expelling their worms, and these worms fully recovered their fecundity after 7 days in recipients. On day 5 of secondary and tertiary infections, immediately before loss of worms began, the adult worms were stunted and had a depressed fecundity. However, such worms, when transplanted, were able to establish in normal numbers and in a normal position in the intestine of recipient mice. Additionally, these worms were found to have developed a fecundity, and grown to a length, comparable to that of normal worms, but slightly less than that of control worms transplanted from day 7 of a primary infection, after 7 days in a new host. Electron microscopy showed that worms taken at the time of expulsion in primary and tertiary infections showed structural abnormalities, including large quantities of lipid in intestinal cells and somatic musculature and decreased quantities of stored glycogen. Upon transplantation to new host mice, these worms were found to have recovered a normal ultrastructural appearance within 7 days, although there was still evidence of a slightly elevated lipid and depressed glycogen content. It is concluded that immune expulsion of T. spiralis from mice does not involve irreversible damage to the worms.

The effect of dietary water content and feeding rate on the growth and food conversion efficiency of turbot ( Scophthalmus maximus L.)

The effect of dietary water content and feeding rate on the growth and food conversion efficiency of turbot was investigated using diets which contained identical amounts of dry nutrient material but different quantities of water, ranging from 0 to 74%. The dietary water content did not significantly influence the growth, composition, condition factor or food conversion efficiency of the turbot. It appeared that, as long as the basic nutrients were formulated so as to produce an adequate diet, the water content was immaterial. The over-riding factor governing growth was the rate of food intake. Comparisons at feeding rates which in energy equivalents ranged from 24 to 72 calories per gram of fish a day, showed that the higher the energy intake the more rapid the growth. At the highest feeding rate, fast growth was accompanied by a marked increase in the condition factor and an elevated lipid content of the fish. The percentage protein content, however, was relatively stable in relation to the feeding rate. Food conversion efficiency was also relatively stable. On average, 40.3% of the dietary protein and 36.3% of the ingested energy was converted into turbot.

Effect of 6-hydroxydopamine and alpha-methyltyrosine on brown adipose tissue of infant rats.

A single-dose administration of 6-hydroxydopamine (50 mg/kg body weight, sc) to infant rats resulted in an enlargement, higher fresh weight, markedly elevated lipid content, and higher total protein content of their interscapular and cervical brown adipose tissue. The protein kinase (EC 2.7.1.37) activation ratio in the tissue was decreased as was the phosphoenolpyruvate carboxykinase (EC 4.1.1.32) activity. Fatty acid synthetase, on the other hand, showed an increased activity. These changes commenced as soon as 24 h after the administration of the drug, were fully developed 2-4 days later, and persisted for at least 14 days. The results are in line with the assumption that 6-hydroxydopamine administration causes chemical sympathectomy of brown adipose tissue. This is further supported by the fact that treatment with alpha-methyltyrosine, which is known to competively inhibit norepinephrine systhesis, results in similar changes in brown fat of infant rats. Hence it seems that 6-hydroxydopamine administration offers a simple and inexpensive experimental model for studies of the role norepinephrine-mediated sympathetic nervous system in brown tissue function and development.

Effect of Diethylstilbestrol and Cholesterol on the Fatty Acid Metabolism of Turkeys

SEVERAL workers (Lorenz, 1944, 1945; Sykes et al., 1945; Gassner and Wilgus, 1948; Bird, 1946; and Herbert and Brunson, 1957) have reported increased fat deposition in cockerels, broilers and turkeys treated with diethylstilbestrol. Reinis et al. (1962) and Malinow et al. (1963) found that diethylstilbestrol greatly elevated serum total lipid, phospholipid and cholesterol contents of cocks and cockerels.Dietary corn oil increased the liver linoleate content and decreased the palmitoleic and oleic acid contents (Marion and Edwards, 1963). Hill (1966) reported that liver trienoic acid content was high when the diet was low in linoleic acid. Trienoic acid content decreased and dienoic and tetraenoic acid contents increased with an increase in dietary linoleate.Previous investigations in our laboratory have shown that plasma oleic acid content of cockerels treated with cholesterol, diethylstilbestrol, and a combination of cholesterol and diethylstilbestrol, increased but the plasma eicosatrienoic acid content was unchanged (Chung et al., .

Rapid accumulation of renal fat in cats after single inhalations of carbon tetrachloride

Carbon tetrachloride administered to cats by inhalation at a concentration of 10,000 ppm elevated renal lipid content to near maximal levels in 15 minutes. Both stainable fat and the chemical fat content of the kidney were high after 30, 60, and 240 minutes' exposure and remained so 3 hours after a 4-hour CCl 4 inhalation. Twenty-four hours later, both the total lipid and stainable fat droplets were below normal. An increase of kidney weight occurred within 60 minutes and was maintained throughout the 24-hour observation period. The total lipid content of cat liver had increased significantly at 3, 12, and 24 hours after a 4-hour CCl 4 exposure. Increased liver weight was observed 24 hours after the withdrawal of CCl 4. Increases in adrenal weight occurred within 30 minutes after CCl 4 inhalation and remained high for periods up to 24 hours after a 4-hour exposure. No sign of fatty change was observed in the adrenal at the time intervals examined. Early increases in both the weight and fat content of cat kidney suggested that the renal effects of CCl 4 are independent of the hepatic changes.