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Biomedical subjects

R C Noble

Publications and source records attributed to R C Noble.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effects of dietary supplementation with alpha-linolenic acid on the phospholipid fatty acid composition and quality of spermatozoa in cockerel from 24 to 72 weeks of age.

The aim of this study was to investigate the effects of supplementing the diet of the male chicken with alpha-linolenic acid (18:3n-3) on the phospholipid fatty acid composition, motility and fertilizing ability of chicken spermatozoa. The birds in the control group received a diet supplemented with soybean oil rich in linoleic acid (18:2n-6) whereas those in the test group were supplemented with linseed oil rich in alpha-linolenic acid. A number of age-related changes in the lipid parameters of the spermatozoa were observed in control birds. Between 24 and 72 weeks of age the amount of total lipid in the spermatozoa of control birds increased by approximately 2.4 times and the proportions of cholesterol and free fatty acid also increased significantly, whereas the proportions of phospholipid and triacylglycerol decreased. In addition, the proportion of phosphatidylcholine in the total phospholipid increased, whereas the proportion of phosphatidylserine decreased during the same period. The proportion of docosatetraenoic acid (22:4n-6) in the phospholipid decreased significantly between 24 and 72 weeks of age. The concentration of spermatozoa in the semen of control birds increased to a maximum at week 39 and had decreased significantly by week 72. Supplementation with alpha-linolenic acid had little or no effect on the proportion of docosahexaenoic acid (22:6n-3) in the phospholipid profile of the spermatozoa. However, supplementation with alpha-linolenic acid did produce a significant but small increase in the proportion of docosapentaenoic acid (22:5n-3) recorded at 39 and 54 weeks. Thus, this study shows that the fatty acid composition of the sperm phospholipid demonstrates a marked resistance to dietary manipulation. Supplementation with alpha-linolenic acid significantly enhanced semen fertility at week 39. The results suggest that the small increase in the proportion of n-3 fatty acids in the sperm phospholipids induced by enriching the diet with alpha-linolenic acid is associated with a significant improvement in semen quality at 39 weeks of age.

Animals↗
PubMed1997

The effect of dietary oil containing (n-3) fatty acids on the fatty acid, physicochemical, and organoleptic characteristics of pig meat and fat.

An investigation was made to alter the fatty acid composition of pork and a pork product in line with human dietary advice while not adversely affecting factors controlling consumer acceptability. Pigs (n = 150) were assigned to three dietary treatments with 25 intact male-female pairs per treatment. Diet A (control) contained 3% of a 4:1 (wt/ wt) tallow-soybean oil mixture. Diets B and C contained 2% rapeseed oil plus 1% fish oil. Diets A, B, and C were supplemented with 100, 100, and 250 mg of all-rac-alpha-tocopheryl acetate/kg of diet, respectively. Pigs were given ad libitum access to feed from 52 kg live weight until 95 kg (slaughter). Sausages were prepared from the resulting cuts. Tissues of pigs were evaluated in terms of fat firmness, color, fatty acid composition, and contents of alpha-tocopherol and thiobarbituric acid-reactive substances (TBARS). Organoleptic characteristics of chops and sausages were evaluated by a trained taste panel. Pigs fed Diets B and C had improved feed conversion ratios (P < .05) and ADG compared with control pigs. The levels of n-3 (omega-3) polyunsaturates were significantly increased in the tissues and sausage from pigs fed Diets B and C with associated alterations in n-6 to n-3 fatty acid ratios that accorded with contemporary human dietary recommendations. Levels of alpha-tocopherol and TBARS were significantly altered in the tissues. There were no appreciable differences between treatments in carcass characteristics, including color. The overall organoleptic acceptability of chops and sausages was not different between the treatments.

Animals↗
PubMed1996

Tissue-specific differences in antioxidant distribution and susceptibility to lipid peroxidation during development of the chick embryo.

The purpose of this study was to determine the tissue-specific acquisition of antioxidant capacity during chick embryo development and to assess the effectiveness of this process in the prevention of lipid peroxidation. The transfer of alpha-tocopherol, carotenoids and ascorbic acid from the yolk/yolk sac membrane (YSM) to the developing chick embryo and the distribution of these antioxidant compounds between the embryonic tissues were investigated. The concentrations of alpha-tocopherol and carotenoids in the yolk decreased between day 15 of development and hatching at day 21, concomitant with an increase in the levels of these antioxidants in the YSM. The concentration of both these lipid-soluble antioxidants in the liver increased dramatically between day 18 of embryonic development and day 1 after hatching. The adipose tissue content of alpha-tocopherol also increased markedly during the late embryonic/early neonatal period. However, the levels of alpha-tocopherol in the liver were far higher than in any other tissue with particularly low levels observed for the brain. Also, carotenoids were undetectable in the developing brain. Ascorbic acid was not present in the initial yolk but high levels of this water-soluble antioxidant were detected in the YSM, particularly at the early stages of development. The concentration of ascorbic acid in the embryonic brain was far higher than in any other tissue. Homogenates of brain tissue were extremely susceptible to lipid peroxidation during incubation in vitro whereas extracts of liver, yolk and YSM were relatively resistant to lipid peroxidation, particularly in the absence of exogenous Fe2+.

Animals↗
PubMed1996

Changes in the size and docosahexaenoic acid content of adipocytes during chick embryo development.

The development of adipose tissue in the chick embryo was investigated using two groups of fertile eggs which differed by 1.7-fold in their initial yolk lipid levels. The triacylglycerol content of the subcutaneous adipose depot in both groups increased dramatically from day 12 of the 21-day embryonic period, attaining a maximal value just prior to hatching. During this period, the amount of triacylglycerol deposited in the adipose tissue was very highly correlated with the amount of lipid transferred from the yolk. The triacylglycerol content of the depot was also dependent on the initial yolk lipid content. During the hatching period, the amount of adipose triacylglycerol remained approximately constant in the group with the higher initial yolk lipid content but, in the case of the group with the lower initial yolk lipid levels, decreased by approximately 25%. The size distribution of adipocytes isolated from the tissue was determined by computerized image analysis microscopy. The mean adipocyte diameter increased from approximately 6 to 35 microns between days 12 and 19, irrespective of the initial yolk content, although development within the eggs with the lower initial yolk content resulted in a decrease in cell size over the hatching period. Both the triacylglycerol and phospholipid fractions of the isolated adipocytes contained substantial proportions (approximately 6%, w/w) of docosahexaenoic acid (DHA) at days 12 and 14, and lower levels of this fatty acid at the later stages. The amount (mg/depot) of DHA in adipose triacylglycerol decreased dramatically over the hatching period. The amount (mg/brain) of DHA in brain phospholipid increased by more than 5-fold between day 12 of development and hatching. A possible explanation for the data may be that DHA is preferentially mobilized from adipose tissue in order to deliver the fatty acid to the developing neural tissues in a form suitable for uptake.

Adipocytes↗
PubMed1996

The fatty acid composition of brain phospholipids from chicken and duck embryos.

The effects of differences in the fatty acid composition of the lipids of egg yolk on the subsequent levels of arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) in the total phospholipids and in the isolated phospholipid classes of the embryonic brain were investigated by a comparison of two domesticated avain species, the chicken and the duck. The yolk phospholipids of chicken eggs contained similar proportions of 20:4n-6 and 22:6n-3 (approx. 6% wt/wt of total fatty acids). In marked contrast, the yolk phospholipids of commercially produced duck eggs contained an overwhelming preponderance of 20:4n-6 over 22:6n-3 (approx. 10% cf.1%). These differences between the yolks of the two species were only partly reflected in the fatty acid compositions of the total phospholipids of the embryonic brains at equivalent developmental stages. Typically, the chicken brain phospholipids contained approximate proportions of 20:4n-6 and 22:6n-3 of 8% and 17%, respectively, whereas both these polyunsaturates were present at approx. 11% in the duck samples. The brain phospholipids were resolved into their component phospholipid classes by high performance liquid chromatography. In both species, phosphatidylcholine contained only low levels of 20:4n-6 and 22:6n-3, whereas phosphatidylethanolamine displayed a high content of 22:6n-3. Phosphatidylserine was also rich in 22:6n-3 whereas phosphatidylinositol exhibited a high proportion of 20:4n-6. The results suggest that the relatively low level of 22:6n-3 in the yolk of duck eggs is partly compensated for by an enhanced efficiency in the incorporation of this fatty acid into the brain phospholipids, in comparison with the chicken.

Animals↗
PubMed1996

Developmental changes in the levels of molecular species of triacylglycerol that contain docosahexaenoic acid in adipose tissue of the chick embryo.

Triacylglycerols from the initial yolk and from the adipose tissue of the chick embryo were subjected high-performance liquid chromatography in the silver ion mode to resolve molecular species of triacylglycerol on the basis of the degree of unsaturation. A total of 12 such species was resolved from the yolk samples, with only one of these species containing docosahexaenoic acid. In contrast, 17 species were resolved from adipose tissue at day 12 of embryo development, of which 8 contained docosahexaenoic acid. The major species containing this fatty acid consisted of docosahexaenoic acid in combination with palmitic and oleic acids. The amounts of the species consisting of C16 and C18 fatty acids in the adipose tissue increased continuously from day 12 until just before hatching at day 19 and then decreased slightly over the hatching period. In contrast, the amounts within the adipose depot of the species containing docosahexaenoic acid reached a maximal level by day 16 and then decreased dramatically to almost undetectable levels during the hatching period. The possibility that adipose tissue triacylglycerol in the chick embryo may function as a temporary store of docosahexaenoic acid for subsequent delivery to the developing neural tissues is suggested.

Adipose Tissue↗
PubMed1996

Lipid and antioxidant changes in semen of broiler fowl from 25 to 60 weeks of age.

Spermatozoa and seminal plasma from cockerels at the beginning and end of their reproductive periods were examined for their lipid composition and associated antioxidant capacities. The significant reduction in concentration of spermatozoa with age was associated with a large increase in lipid concentrations in spermatozoa and in seminal plasma. This change in lipid concentration was accompanied by increases in the proportions of phospholipid and free cholesterol; in contrast, the proportions of these lipid moieties in seminal plasma were reduced. The major phospholipid fractions in the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. There was a large decrease with age in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline in the spermatozoa and seminal plasma. These major changes in phospholipid content were accompanied by a decrease in the amount of phosphatidyl serine in the spermatozoa and increases in phosphatidyl inositol and cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by considerable reductions in the content of the major polyunsaturated fatty acids 20:4 (n-6) and 22:4 (n-6). The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase. The role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age are discussed.

Aging↗
PubMed1995

The transfer of docosahexaenoic acid from the yolk to the tissues of the chick embryo.

Changes in the amounts of the major fatty acids present in the lipids of the yolk complex and the embryo were delineated during embryogenesis of the chicken. The rates of transfer of palmitic, oleic, linoleic, linolenic and arachidonic acids from the lipids of the yolk complex were essentially identical. In contrast, docosahexaenoic acid (DHA) was preferentially transferred from the yolk complex at a rate which was significantly higher than that exhibited by the other major fatty acids. The rates of accumulation of both arachidonic acid and DHA in the lipids of the whole embryo were significantly greater than the rates observed for the C16 and C18 fatty acids, particularly between days 12 and 16 of the 21-day embryonic period. Analysis of the fatty acid composition of plasma lipid throughout development indicated that the triacylglycerol fraction contained relatively high proportions (up to approx. 14% w/w of total fatty acids) of DHA, but much lower proportions (approx. 3%) of arachidonic acid. In contrast, plasma phospholipid was enriched in arachidonic acid (up to approx. 18%), but contained much lower proportions (generally less than 3%) of DHA. A considerable amount of DHA was incorporated into adipose tissue triacylglycerol, so that by the time of hatching, the tissue represented a major store of this fatty acid. Over the hatching period, the amount of DHA in adipose triacylglycerol decreased dramatically, by up to 85%, whereas there was little or no change in the amounts of the other major fatty acyl components in this tissue. The amount of DHA as a component of brain phospholipid increased continuously throughout the developmental period studied. However, by the time of hatching, the amount of DHA in brain phospholipid represented less than 10% of the amount of this fatty acid originally present in the lipids of the yolk.

Adipose Tissue↗
PubMed1995

Ehrlichiosis in Kentucky.

Ehrlichiosis is a recently described tick-borne disease characterized by headache, fever and chills, leukopenia, thrombocytopenia, and transaminase elevation. The presentation is similar to Rocky Mountain spotted fever but the rash is less frequently present in ehrlichiosis. The diagnosis is confirmed by elevated antibody titers to Ehrlichia chaffeensis or visualization of inclusions in white blood cells and the disease is easily cured with tetracyclines or chloramphenicol. Cases of ehrlichiosis are reported from southeastern, southcentral and midatlantic states. We report three cases of Ehrlichia infection acquired in Pulaski County and Fort Knox, KY during 1992-93.

Adult↗
PubMed1994

The esterification of cholesterol in the liver of the chick embryo.

The development of the chick embryo was characterised by the accumulation of large droplets of lipid in the cytoplasm of the embryonic liver, as revealed by electron microscopy. Analysis of the lipid composition of the livers indicated that this accumulation resulted from a dramatic increase in the cholesteryl ester content of the tissue during the the latter part of the embryonic period. This lipid is apparently derived from yolk cholesterol and may be taken up by the liver in the form of lipoprotein remnants. Significant levels of acyl-CoA: cholesterol acyltransferase (ACAT) activity were expressed in the liver throughout the second half of the developmental period, and this activity was maximal at the time when lipid transfer from the yolk was most intensive. The activity of microsomal cholesterol ester hydrolase (CEH) was very low throughout development, and no CEH activity was detected in the cytosolic fraction. In addition, substantial amounts of a cytosolic protein which inhibits CEH activity were present. Thus the relative activities of these enzymic systems are consistent with the net accumulation of cholesteryl ester which occurs in the liver during development.

Animals↗
PubMed1994

Pseudomonas stutzeri infection. A review of hospital isolates and a review of the literature.

Pseudomonas stutzeri is uncommonly isolated from patients and rarely causes disease. Clinical isolates of P. stutzeri from a university hospital were reviewed over a 16-year period. In the hospital review, only three patients were identified with P. stutzeri infection, and in only one of these was the organism present as the sole isolate. A review of the literature shows that P. stutzeri is most frequently isolated from blood, wounds, the respiratory tract, and urine. Patients with P. stutzeri infections often have serious underlying disease but generally respond to treatment with antibiotics including the aminoglycosides, the antipseudomonal penicillins, trimethoprim-sulfamethoxazole, and the third-generation cephalosporins.

Adult↗
PubMed1993

Tissue-specific changes in lipid composition and lipoprotein lipase activity during the development of the chick embryo.

Lipoprotein lipase was present at a high specific activity in adipose tissue and heart of the chick embryo at the 14th day of development. The enzyme was also present in skeletal muscle but was absent from brain and liver. Major increases in the activity of lipoprotein lipase in adipose tissue and heart occurred from day 12 of development, concomitant with the beginning of the period of lipid uptake from the yolk. These results suggest that lipoprotein lipase may be involved in the utilisation of yolk-derived lipid by the tissues of the embryo. Relatively high levels of docosahexaenoic acid (22:6(n--3)) were present in the triacylglycerol isolated from plasma, adipose tissue, heart and liver. The relative proportions of this fatty acid in the triacylglycerol of the different tissues may be explicable in terms of the substrate specificity of lipoprotein lipase.

Adipose Tissue↗
PubMed1993

The esterification of cholesterol in the yolk sac membrane of the chick embryo.

The uptake of lipid from the yolk by the yolk sac membrane of the chick embryo is accompanied by the rapid esterification of a large proportion of the yolk cholesterol. This could arise from enhanced acyl-CoA:cholesterol acyltransferase (ACAT) activity and/or inhibition of cholesteryl ester hydrolase (CEH) activity. The activity of ACAT was therefore measured in microsomes obtained from yolk sac membranes at various stages of development. A high level of activity (up to 929 pmol of cholesteryl oleate formed per min per mg protein) was found during the second half of this period. Supplementation with exogenous cholesterol stimulated ACAT activity in microsomes obtained from the tissue at the earlier, but not at the later, stages of development suggesting that the enzyme became saturated with microsomal cholesterol as development proceeded. Correlating with this, the concentration of cholesterol in the microsomes increased 4-fold between 9 and 20 d of development. The activity of CEH was very low in the microsomes and could not be detected in the cytosolic fraction. The activity of a protein, which has been shown to function as an inhibitor of CEH, was found to be present at all stages of development. The high activity of ACAT, together with the low activity of CEH and an active CEH inhibitor protein is a combination well suited to promote an essentially unidirectional conversion of cholesterol to cholesteryl ester. This process may be a major determinant of the rate of lipid transfer from the yolk to the embryo.

Animals↗