481 |
Effect of vitamin B-6 status on fatty acid and lipid metabolism in womenKim, Min Sun, 1971- 08 May 1997 (has links)
The effect of vitamin B-6 (B-6) status on plasma fatty acids (FA) levels and lipid
metabolism was investigated in this metabolic study. Eight female subjects were fed for 28
days. For the first 7 days, they were fed a constant diet containing 2.10 mg of B-6. For the
rest of the period (21 days), they were differentiated in terms of B-6 intake; 4 of them
were fed a low (0.93 mg/day) and 4 a high (2.60 mg/day) B-6 diet. B-6 status indices,
plasma FA concentration and lipid profile were determined.
Plasma pyridoxal 5'-phosphate and total B-6 concentration (P<0.01), urinary 4-
pyridoxic acid and total B-6 concentration (P<0.001) showed a significant difference
between the two groups at the end of the study. Erythrocyte PLP failed to show any
significant difference between the two groups throughout the diet study.
There was no significant difference in the plasma FA or lipid profile between the
two groups. Plasma total cholesterol (TC) of the low B-6 group decreased slightly (7 %),
but was not statistically significant. When comparing day 7 and day 28 values, plasma
triglycerides increased (9 %) for the high and decreased for the low B-6 group. LDL-C
decreased (5 %) for the high B-6 group but did not change in the low B-6 group. HDL-C
decreased slightly in both groups (~8 %).
There was no clear evidence that a low intake of vitamin B-6 affects the fatty acid
and lipid metabolism. Further studies are required to identify the relationship between
vitamin B-6 and fatty acid and lipid metabolism in humans. / Graduation date: 1997
|
482 |
Effects of cyclopropenoid fatty acids on liver plasma membranes of rainbow trout (Salmo gairdneri)Marino, Donald R. (Donald Robert) 31 October 1988 (has links)
Cyclopropenoid fatty acids (CPFA), which are a group of
fatty acids produced by plants of the order Malvales, are known
to induce adverse physiological effects when administered to a
variety of animal species. A structurally strained cyclopropene
ring is present in all CPFA and is believed responsible for the
toxic action of these fatty acids. Dietary consumption of CPFA
by mammals, poultry and fish has resulted in toxic responses
including hepatic damage, impaired reproductive capabilities and
sizeable alterations in lipid metabolism. Furthermore, CPFA
have been identified as mildly carcinogenic and strongly
cocarcinogenic towards rainbow trout (Salmo gairdneri). The
mechanism by which CPFA enhance carcinogenesis is currently not
understood. The research in this thesis has therefore been
directed toward obtaining a better understanding as to how CPFA
induce toxic responses in rainbow trout.
Hepatic plasma membranes were isolated from both control
trout and trout which had consumed dietary CPFA. The plasma
membranes were then compared via the use of electron microscopy,
chromatographic analysis of phospholipid and fatty acid
content, two dimensional polyacrylamide gel electrophoresis of
proteins, and Western blot analysis of concanavalin A sensitive
glycoproteins. Electron micrographs revealed that control
plasma membranes appeared more homogeneous than CPFA membranes
and were characterized by more membrane sheets and less
vesicularization. The analysis of enzyme activities revealed
that CPFA caused a decrease in whole liver glucose-6-phosphatase
activity and that control plasma membranes expressed slightly
higher glucose-6-phosphatase and 5'-nucleotidase activities as
compared to CPFA membranes. Although dietary CPFA appeared to
have no effect on the phospholipid content of the plasma
membranes, significant alterations in the fatty acid profiles
of ethanolamine and choline phospholipids were observed. CPFA
caused a decrease in palmitic, palmitoleic and oleic acids while
the level of stearic and docosahexaenoic acids subsequently
increased. Differences between the protein content of control
and CPFA plasma membranes were made clear through the analysis
of electrophoretic and Western blotting data. Membranes
isolated from fish fed CPFA contained several proteins of high
molecular weight (above 66,000 daltons) and other proteins of
high isoelectric point that were not present in control plasma
membranes. Additionally, two families of glycoproteins which
had previously been identified as microsomal in origin were detected only in CPFA plasma membranes. A discussion concerning the possible causes and biological ramifications of
the observed subcellular alterations caused by CPFA insult is
also presented in this thesis. / Graduation date: 1989
|
483 |
Peroxidase and lipoxygenase activities and their effect on the stability of polyunsaturated fatty acids in two different varieties of sweet corn (Zea mays L.), Jubilee and GH 2684, during frozen storageRodriguez-Saona, Luis Enrique 01 October 1993 (has links)
The effect of different blanching treatments and
packaging materials on the enzymatic (lipoxygenase and
peroxidase) activity and fatty acid stability of two
different varieties of sweet corn on the cob (Jubilee and GH
2684) was evaluated during nine months of frozen storage at
-23.3°C.
The initial moisture content in the kernels of the two
sweet corn varieties averaged 72.5%. After nine months of
frozen storage the moisture content in the kernels of corn
depended greatly on the packaging material used. The ears
stored in Cryovac B and E bags showed the best moisture
retention (72.2% final moisture content), followed by the
polyethylene bags (71.4%) while the ears stored without
packaging material showed severe dehydration (70.1%).
The peroxidase and lipoxygenase activities were
determined using spectrophotometric assays on a crude
extract obtained from liquid nitrogen powdered corn. Both
unblanched varieties of sweet corn showed similar initial
peroxidase specific activity and general behavior during the
nine months of frozen storage. The presence of lipoxygenase
isozymes with different thermal stabilities in both
varieties was suggested by the higher lipoxygenase specific
activity found in Jubilee after freezing and nine months of
frozen storage (0.135 units/mg protein) compared with the GH
2684 variety (0.115 units/mg protein).
Complete inactivation of lipoxygenase was obtained
after 9 minutes steam blanching at 100°C. Peroxidase was
more heat resistant showing some remaining specific activity
after 9 minutes steam blanching with a complete inactivation
after 15 minutes steam blanching. No regeneration of either
enzyme was observed during the nine months of frozen storage
suggesting a permanent disruption of the active site of both
enzymes.
Relative fatty acid content was determined by gas
chromatographic analysis of fatty acids methyl esters. The
major fatty acids present in both varieties were palmitic
(14.93%), stearic (2.79%), oleic (31.54%), linoleic
(46.87%) and linolenic (1.89%) acids. Good stability of
the polyunsaturated fatty acids was observed during the nine
months storage at -23.3°C, with autoxidation as the main
mechanism responsible for the decrease in the relative percent of polyunsaturated fatty acids. Some enzymatic
oxidation also occurred, decreasing the linolenic acid
content.
The control of the degradation of polyunsaturated fatty
acids depended mostly on the frozen storage temperature
(-23.3°C) and not on the oxygen permeability of the different
packaging materials.
The results obtained in our study suggested that
blanching of the ears of sweet corn had an important effect
on reducing the enzyme activity but little effect on the
polyunsaturated fatty acid degradation after 9 months of
storage at -23.3°C. / Graduation date: 1994
|
484 |
A study of the DNA excision repair capabilities of rainbow trout (Salmo gairdneri) exposed to dietary cyclopropenoid fatty acidsCollier, John Mark 30 June 1988 (has links)
The DNA repair capabilities of rainbow trout (Salmo gairdneri)
were studied vising the method of autoradiography. Trout were fed a
semi-purified control diet containing 0 ppm, 50 ppm, or 300 ppm
cyclopropenoid fatty acids (CPFA) for 6-9 weeks. Liver slices were
prepared and exposed in vitro to a control treatment, ultraviolet
irradiation (UV), ethidium bromide (EB), UV/EB in succession, or
aflatoxin B₁. The degree of DNA repair was analyzed in terms of
net grains per cell.
Except following the EB treatment, fish on the control diet
revealed an absence of ongoing DNA repair. Trout fed 50 ppm CPFA
exhibited a consistently low level of repair over time following the
in vitro control treatment. Fish fed 300 ppm CPFA revealed a
relatively higher degree of ³H-Me-thymidine incorporation
indicative of induced DNA repair following the in vitro control
treatment, and the degree of repair increased with time on the diet. UV-irradiation caused a marked increase in the degree of induced DNA
repair in 300 ppm CPFA fish at 6 and 7.5 weeks, and in 50 ppm CPFA
fish at 7.5 weeks. Follcwing UV-irradiation, liver slices were
exposed to EB, a DNA intercalating agent used to inhibit normal DNA
replication. However, in contrast to the desired effect, EB caused a
marked decrease in the degree of repair synthesis observed in 300 ppm
CPFA fish at 6 and 7.5 weeks. Indicative of intercalation, the in
vitro EB treatment caused a moderate degree of ³H-Me-thymidine
incorporation in fish fed the control diet. Repair was also induced
in 300 ppm CPFA fish following exposure to EB at 6 and 7.5 weeks.
Aflatoxin B₁ induced DNA repair to various degrees in fish on all
diets at 7.5 and 9 weeks. In comparison to the in vitro control
treatment, it was observed that the degree of induced DNA repair was
decreased significantly - "completely" following the UV, UV/EB, and
EB treatments - in fish fed the 300 ppm CPFA diet for 9 weeks.
In view of the low level of DNA repair observed in rainbow trout
using autoradiography, the repair capabilities were studied using a
more sensitive assay, bromodeoxyuridine (BrdU) photolysis. Isolated
hepatocytes were prepared from fish fed the various diets and exposed
in vitro to a control treatment, UV-irradiation, or
4-nitroquinoline-N-oxide. The obtained results were nonconclusive
indicating technical improvements on the assay need to be made. / Graduation date: 1988
|
485 |
Studies of the effects of dietary lipid manipulation upon blood lipids and immune cell functionJeffery, Nicola January 1996 (has links)
No description available.
|
486 |
Anticonvulsant Effects of Omega-3 Polyunsaturated Fatty Acids in RodentsTaha, Ameer 17 January 2012 (has links)
The present research examined the hypothesis that omega-3 polyunsaturated fatty acids would increase seizure threshold in rats in vivo, and reduce neuronal excitability in mouse hippocampal slices. Seizure thresholds were measured in rats using the maximal pentylenetetrazol and electrical stimulation seizure tests following α-linolenic acid (ALA) or docosahexaenoic acid administration. ALA raised seizure threshold in the maximal PTZ seizure test, but this effect probably occurred because ALA displaced DHA from liver to the brain. DHA itself was therefore tested in the PTZ and electrical stimulation seizure tests. Direct administration of DHA by subcutaneous injection raised seizure thresholds in the PTZ seizure test, which models tonic-clonic attacks in humans. Dietary enrichment with DHA raised afterdischarge seizure thresholds in the cortex and amygdala, which model simplex and complex partial seizures in humans, although this effect took some time to occur. In vitro, the application of DHA also reduced the incidence of excitatory sharp waves in mouse hippocampal slices. This effect did not appear to be due to either an increase in GABAergic inhibitory tone, nor to a decrease in glutamatergic drive. The fatty acid composition of phospholipids and unesterified fatty acids were measured in the brain following microwave fixation in order to determine whether the effects of DHA on seizure thresholds were due to its de-esterification from the phospholipid membrane. The assay surprisingly revealed that subcutaneous administration of DHA at a dose that raised seizure threshold, increased unesterified arachidonic acid, but not unesterified DHA concentrations during seizures. The results of these studies support the hypothesis that DHA raises seizure threshold in rats, and reduces neuronal excitability in vitro. The effects of DHA on seizure threshold are possibly mediated by the de-esterification of arachidonic acid, which is known to have effects on the voltage-dependent sodium channel.
|
487 |
A kinetic study of fatty acid desaturation in penicillium chrysogenumChamberlin, Paul T. January 1971 (has links)
The effects of oxygen, malonate, and acetate on the conversion of radioactively-labeled Coenzyme A thioesters of lauric and stearic acids to unsaturated fatty acids by 15,000 x g supernates of Penicilliumlehrysogenum were studied. Following the termination of reactions, the incubation products were saponified, acidified, extracted, and methylated. The resulting methyl esters were purified, separated, identified, and collected. Radioactivities of each fatty acid fraction were determined and converted to percentage of total radioactivity recovered.Desaturase activity was virtually non-existent in the anaerobic incubations indicating that this organism utilized the aerobic pathway of desaturation. The absence of acetate and malonate from incubation mixtures of either laurate or stearate markedly decreased the overall desaturase activity and the amount of linoleate produced. The failure of labeled laurate to be converted to long-chain unsaturated fatty acids in the absence of malonate indicates that chainelongation in this organism proceeds by the malonate pathway. The data presented suggest that laurate may be directly desaturated and then elongated to oleate instead of following the typical aerobic pathway. / Department of Biology
|
488 |
Effects of dietary stearic and linoleic acid on mammary carcinogenesis and longevity of aging strain A/ST miceRogers, Wendy J. January 1998 (has links)
This investigation studies the effects of diets containing varying amounts of linoleic acid (a polyunsaturated fatty acid) and stearic acid (a saturated fatty acid) on tumorigenesis, weight and longevity in strain A/ST mice. Linoleic acid [ 18 carbons and 2 double bonds (18:2)] was chosen to represent a fatty acid known to enhance tumorigenesis and obesity in certain strains of mice. Stearic acid [ 18 carbons and no double bonds (18:0)] represents a saturated fatty acid known to increase the latency period for mammary tumor development and to decrease the rate of tumor growth. This study was conducted to determine whether the effects of fatty acids observed in younger mice on time to tumor, survival and body weights were also found in aging animals. Further, by varying the amount of linoleic acid in the diet, this study examined whether the tumor enhancing effects of increasing amounts of linoleic acid could be overcome by the incorporation of dietary stearic acid. All diets had equal percentages, by weight, of protein, salt, sucrose, mineral salt, and vitamin levels and an equal number of calories per gram of food. The SF diet was rich in linoleic acid. The SA-1 diet contained enough linoleic acid to prevent essential fatty acid deficiency, and the SA-4 diet contained the maximal amount of linoleic acid for tumor enhancement. Total body weight and tumor production in the three dietary groups show a relationship between an increase in body weight and tumor production as the amount of dietary linoleic acid increases. There also is an inverse relationship between animal survival and body weight as the amount of dietary linoleic acid increases. Survival thus appears to be dependent on tumor production in the three dietary groups, where there appears to be an inverse relationship between survival and time to tumor as the amount of dietary linoleic acid increases at each timepoint. These results suggest that the inclusion of stearic acid in the diet can, in part, overcome this enhancing effect of linoleic acid, even at the optimal tumor producing level of linoleic acid. The results of this study indicate that that effects of linoleic and stearic acid in aging mice are similar to those in younger animals. / Department of Biology
|
489 |
The effects of dietary long chain n-3 polyunsaturated fatty acids on soluble epoxide hydrolase and related markers of cardiovascular healthMavrommatis, Ioannis January 2009 (has links)
Preliminary data from studies in rodents suggests time-dependent associations between dietary LC n-3 PUFA and hepatic levels of the enzyme soluble epoxide hydrolase (sEH), which regulates the metabolism and availability of epoxyeicosatrienoic acids (EET). EET are cytochrome P450 epoxygenase products of arachidonic acid associated with lower blood pressure, decreased inflammatory response and inhibition of blood coagulation. To further investigate the association between LC n-3 PUFA and sEH, ApoE<sup>-</sup>/<sup>-</sup> mice were fed a high-fat high-cholesterol diet supplemented with either fish oil (EPA + DHA) or DHA or HOSF (all 2% w/w) for 10 weeks and livers and aortic roots were collected on day 2 and weeks 1, 2, 4 and 10. Proteomics analysis showed an overall decreasing effect of fish oil (but not DHA) supplementation on hepatic protein levels of sEH compared to the control throughout the intervention period (<i>P</i> < 0.05). Neither fish oil nor DHA intervention affected atherosclerotic plaque size in the aortic root. We also examined how dietary supplementation with 1 g/day EPA or 1 g/day DHA for 10 days affects platelet sEH levels and platelet aggregation compared to 1 g/day HOSF (control) in healthy volunteers in a double-blind, placebo-controlled, cross-over trial. We found that DHA decreased platelet aggregation by 10% (<i>P =</i> 0.04) and EPA also inhibited ADP (5 μM)-induced platelet aggregation by 14% compared to the control group but this effect did not reach statistical significance due to high variability between subjects. EPA decreased platelet sEH levels by 25% (not significant), whereas DHA had no effect. We also attempted to optimize a method for measuring EET in plasma and platelets. However, the rapid conversion of EET to other compounds and their low concentration in tissues prevented us from optimizing such a method within the time limits of the project.
|
490 |
The effects of endocannabinoids and fatty acids on lipid metabolism and mitochondrial function in adipocytesSiemens, Linda 12 April 2016 (has links)
The endocannabinoid (EC) system has a role in metabolic homeostasis. The purpose
of this study was to determine the effect of ECs and the fatty acids they are derived
from on lipid metabolism and mitochondrial function in adipocytes. 3T3-L1
adipocytes on day 8 of differentiation were treated with ECs and fatty acids for 48
hours in the absence or presence of insulin and various inhibitors. Lysates were
analyzed via Western immunoblotting, a lipolysis assay and Seahorse XF Analyzer
for changes in protein levels, phosphorylation state, lipolysis, and oxygen
consumption rate. Results showed that ECs (2-arachidonoyl glycerol) stimulated
lipolysis via a novel AMPK-dependent pathway, while fatty acids had varying effects
on insulin signaling and mitochondrial function . These data suggest adipose tissue
EC receptors may be a suitable target for anti-obesity therapy. Further research is
needed to understand how the dietary fatty acid profile may influence synthesis of
ECs. / May 2016
|
Page generated in 0.0373 seconds