Handling and storage of human milk specimens for research.
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Circadian Rhythm↗
Biomedical subjects
J Bitman
Publications and source records attributed to J Bitman.
Lipases and lipids in human milk: effect of freeze-thawing and storage.
Frozen storage is often used by milk banks to preserve expressed human milk for later use. Optimal storage and handling conditions which ensure minimum alteration of lipid composition have not been well defined. Therefore we investigated the effect of rapid freeze-thawing and storage conditions (-20 and -70 degrees C) on the free fatty acid (FFA) levels and on the activities of lipoprotein lipase (LPL) and bile salt-stimulated lipase (BSSL) in human milk. Since during mechanical expression leakage of serum components into milk may occur, we also investigated the effect of the presence of serum on human milk LPL during storage. Lipase activity levels were unaffected by rapid freeze-thawing (x3) followed by storage for 1 month at -20 or -70 degrees C. LPL activity (nmol FFA released/ml milk/min) was 414 +/- 128, 451 +/- 37, and 351 +/- 20 and BSSL activity (mumol FFA/ml milk/min) was 5.7 +/- 0.7, 5.5 +/- 0.8, and 5.7 +/- 0.2 in fresh, freeze-thawed, and stored milk, respectively. FFA levels (% of total lipid) were 3.01 +/- 1.05 and 10.3 +/- 1.6 in fresh-frozen milk stored at -70 and -20 degrees C for 5 months, and 3.78 +/- 1.08 and 13.60 +/- 1.25 in specimens of freeze-thawed (x3) before storage at -70 or -20 degrees C. Addition of serum had no effect on milk LPL at either temperature. We conclude that LPL and BSSL remain fully active during frozen storage of human milk and that milk fat is hydrolyzed at -20 degrees C but not at -70 degrees C. We suggest that banked human milk be stored routinely at -70 degrees C.
Bile Acids and Salts↗
Circadian and ultradian temperature rhythms of lactating dairy cows.
Thermistors were implanted in the right front quarter of udder and peritoneal cavity of six lactating Holstein cows to investigate whether udder temperature is regulated independently of deep body temperature. Sequential measurements of udder, body, chamber, and outdoor temperatures were every 1.4 min (1024 readings/probe per 24 h) by digital computer. Cows were housed (except for short exercise periods) in a chamber at 16.7 +/- .3 degrees C, lights on 0730 to 1630 and 2100 to 0200 h. Temperature was monitored continuously for 5 days in three cows in early lactation and in three cows in late lactation. Udder temperature was closely correlated with body temperature (body and udder temperatures were 38.8 +/- .1 degree C). Five of six cows showed two patterns of temperature variation: a 24-h pattern with two troughs each day--minimum at 0930 to 1100 h, increase 1.0 degree C by 1200 to 1300 h, decline 1 degree C from 2000 to 2200 h, second minimum by 2100 to 2200 h, and constant elevation from 2300 to 0800 h (peak to trough, 1.23 +/- .09 degrees C); and superimposed upon the 24-h rhythm was an ultradian rhythm with an approximate 90 min period (peak to trough, .5 +/- .03 degrees C). Rhythmicity of udder and body temperatures should be considered in research on the chronobiology of milk secretion and mastitis.
Animals↗
Triiodothyronine and thyroxine during gestation in dairy cattle selected for high and low milk production.
Circulating thyroxine, triiodothyronine, and prolactin were analyzed by radioimmunoassay from two groups of pregnant heifers representing genetic populations that differed by 685 kg milk in their first lactation. At 100 days of gestation, blood samples were taken every 15 min for prolactin assay and every 2 h to determine variations of thyroid hormone serum concentration from 0800 to 2000. Basal serum prolactin concentrations in the two genetic groups were not significantly different. A pattern was consistent for both triiodothyronine and thyroxine; concentrations were lower in the morning and higher during the afternoon. Serum triiodothyronine means were not different in the high-producing (1.84 ng/ml) and low-producing heifers (1.86 ng/ml). Serum thyroxine concentrations were significantly higher in the low-producing heifers (67.84 ng/ml) than in high-producing heifers (59.18 ng/ml). The higher thyroxine concentration in pregnant heifers with lower producing ability suggests a negative relationship of thyroxine to milk yield potential.
Animals↗
Blood and milk lipid responses induced by growth hormone administration in lactating cows.
Nine multiparous Holstein cows (average 5.8 yr, 63 to 132 days postpartum) were in a 28-day single reversal experiment in the Beltsville open circuit respiration chambers with two 14-day injection periods (placebo versus bovine growth hormone, 51.5 IU/day). With growth hormone treatment, milk fat percentage increased 25 to 29%, milk fat yield increased 41%, and cows averaged -13.7 Mcal/day energy balance. There were small increases of triglycerides and 1,2-diglycerides, core lipids, and small decreases of cholesterol and phospholipids, the membrane lipids. Fat from growth hormone treatment had 6% less short (6:0, 8:0, 10:0) and medium (12:0, 14:0, 14:1, 15:0, 16:0) chain fatty acids and 6% more long chain 18:1 fatty acids. Plasma of cows treated with growth hormone had an increase of concentrations of free fatty acids, but no shifts were apparent among other lipid classes. Analysis of total plasma fatty acids did not show any net changes, but within individual plasma lipid classes, 18:1 increased and 18:2 decreased. Overall changes of blood and milk lipids are consistent with the concept that adipose tissue reserves were mobilized in response to hormone treatment and that these mobilized lipids were the major carbon source for the 41% increase of milk fat secretion. Increases of de novo synthesis of short and medium chain fatty acids also occurred but much less. Cows treated with growth hormone were in negative energy balance, and the mechanism may differ when cows are in positive energy balance.
Animals↗
The effect of feeding di-(2-ethylhexyl) phthalate and related compounds on lipids in the laying hen.
Di-(2-ethylhexyl) phthalate (DEHP) and three structurally related side-chain analogs were fed to laying hens to determine relationships of structure to effects on lipid metabolism. Hubbard broiler breeder hens were fed either a standard laying mash control diet or the control diet containing DEHP, 2-ethylhexanol (2-EH), 2-ethylhexanal (2-EHALD), or 2-ethylhexanoic acid (2-EHA). Experimental treatments lowered feed consumption, body weight, and egg production. The DEHP and side-chain analog diets lowered plasma total lipids. DEHP, 2% 2-EH, and 1% 2-EHA diets lowered plasma free cholesterol. Liver weights were not significantly changed, but liver fat was reduced. Lipid classes were measured by quantitative thin layer chromatography densitometry. The decreases observed in plasma lipids occurred primarily in the triglyceride fraction. Liver lipid decreases occurred mainly in triglyceride and free fatty acid classes. Hen egg yolk percent fat, lipid classes, and free and total cholesterol were unaffected by any DEHP or side-chain analog diets. Plasma and liver hypolipidemic effects were observed with all of the oxidation state structural analogs of DEHP's side chain, but 2% 2-EH was the most effective treatment. These results suggest that the active portion of DEHP may be the metabolite, 2-EH, formed in vivo by hydrolysis of DEHP's ester bond.
Aldehydes↗
Comparison of the lipid composition of breast milk from mothers of term and preterm infants.
Milk was collected from mothers of 18 very premature (26 to 30 wk gestation age), 28 premature (31 to 36 wk), and six term (37 + wk) infants on day 2 to 3 (colostrum), and at 1, 3, 6, and 12 wk postpartum. Fat content for 154 milk samples was 2.80 g/dl gravimetrically and 2.66 g/dl by quantitative thin-layer chromatography. Fat content increased during lactation, whereas phospholipids and cholesterol declined. Concentrations of medium-chain fatty acids increased from colostrum to mature milk and were highest in preterm milk. Compensatory decreases were observed in very premature and premature oleic acid. Long-chain polyunsaturated fatty acids were highest in colostrum and reduced in mature milk. Long-chain polyunsaturated fatty acids were also higher in very premature and premature milk than in term milk. These elevated levels of readily absorbed medium-chain fatty acids and long-chain polyunsaturated fatty acids in preterm milk may be of special benefit for the needs of premature infants.
Adolescent↗
Lipolysis of triglycerides of human milk during storage at low temperatures: a note of caution.
Human milk samples were divided at collection and stored at -70 degrees C or -20 degrees C, or extracted immediately with organic solvent, to compare lipid class composition. Storage at -20 degrees C was not satisfactory for maintaining milk lipid composition, for it resulted in hydrolysis of triglycerides and the appearance of free fatty acids.
Fatty Acids, Nonesterified↗
Changes in plasma concentrations of thyroxine, triiodothyronine, cholesterol and total lipid in beef steers fed ronnel.
An experiment with eight beef steers was conducted to determine the patterns of change for plasma concentrations of thyroxine (T4), triiodothyronine (T3), cholesterol and total lipid following the addition or withdrawal of the organophosphate, ronnel, from the diet. Steers were fed 0, 2, 4 and 8 mg ronnel/kg body weight daily in a Latin square arrangement of treatments with five 28-d periods. Plasma samples were obtained at -2, 1, 3, 5, 7, 9, 16 and 23 d of each period. Steers had not received ronnel before period 1 and, for periods 2 to 5, steers previously fed the lower levels (0 and 2 mg ronnel) were switched to the higher levels (4 and 8 mg ronnel) and steers previously fed the higher levels were switched to the lower levels. Treatment assignments for periods 1 and 5 were the same. Feed intake was similar for all treatments (7.8 kg/d) and daily gain was greater when ronnel was fed (.65 vs .88 kg). Plasma T4 concentrations increased positively in response to ronnel level within the first day after ronnel feeding began and reached a plateau within 3 d. Plasma T4 concentrations decreased following the withdrawal of ronnel, but the response was slower; a lower level being established within about 7 d. Changes in plasma T3 concentrations were small, but were concurrent with plasma T4 changes and were inversely related to ronnel level. Plasma cholesterol concentrations tended to be positively related to ronnel level, but changed slowly with time; plasma total lipid concentrations were not consistently affected by ronnel level. The results of this experiment demonstrate that ronnel has an immediate effect on thyroid function in beef steers.
Animals↗
Relation of plasma thyroxine and triiodothyronine to body weight in growing male and female Holstein cattle.
Thyroxine and triiodothyronine were measured in blood plasma to determine relationships with growth in male and female Holstein calves at 6, 8, 10, 14, 18, and 22 wk of age. Average initial body weights at 6 wk for male and female calves were 54 and 50 kg. Thyroxine and triiodothyronine were determined by specific double antibody radioimmunoassay on eight calves of each sex at each age. Sexes differed for body weight gains from 6 to 22 wk, average daily gains for males were .93 kg/day and for females .73 kg/day. Thyroxine and triiodothyronine concentrations increased gradually (38 and 96%) in both sexes during the 6 to 22 wk and were higher for males than females. Average concentrations of thyroxine and triiodothyronine were 53.3 and 1.21 ng/ml for males and 39.9 and 1.06 ng/ml for females. Thyroxine and triiodothyronine concentrations in blood plasma of male and female dairy calves were positively correlated with body weight during this initial growth period.
Animals↗
Comparison of N,N-dimethyldodecanamine with antibiotics on in vitro cellulose digestion and volatile fatty acid production by ruminal microorganisms.
Eleven antibiotic compounds used in animal production, were compared with N,N-dimethyldodecanamine for their effects on in vitro cellulose digestibility and VFA production. Dose-response data were analyzed statistically to determine the concentration for each compound which would inhibit cellulose digestion of VFA production by 50%, thereby providing a convenient reference point for evaluation of the amine with respect to the antibiotics. Chlortetracycline, oxytetracycline and penicillin inhibited cellulose digestion by 17 to 35% and VFA production by 18 to 26% at concentrations of 2.5 micrograms/ml, while N,N-dimethyldodecanamine and dihydrostreptomycin at concentrations of 10 micrograms/ml inhibited cellulose digestion and VFA production by 5 to 19%. For similar inhibitive effects, bacitracin, chloramphenicol, kanamycin, sulfanilamide and sulfathiazole were required in concentrations of 25 micrograms/ml. Tylosin at a concentration of 1 microgram/ml inhibited cellulose digestion and VFA production by about 80 and 50%, respectively, and monensin was effective at 5 micrograms/ml. In general, compounds of lesser importance for growth promotion in ruminants (sulfathiazole, sulfanilamide and kanamycin) had a less inhibitory effect on cellular digestion and VFA production in vitro. N,N-dimethyldodecanamine was more effective than these compounds but repressed cellulolytic activity less than those antibiotics (chlortetracycline, oxytetraxycline and monensin) that are most effective in improving feed efficiency.
Amines↗
Effect of dietary fat and cholesterol on uptake of oleic acid and triolein by everted sacs of bovine small intestine.
The influence of dietary fats on in vitro lipid absorption by bovine intestine was studied in 14 calves. Holstein bull calves were fed for 16 wk five liquid diets containing skim milk plus either 3.5% milk fat, 3.5% tallow, 3.5% tallow and .2% cholesterol, 7.0% tallow, or 7.0% tallow and .2% cholesterol. Uptake of oleic acid or triolein by everted jejunal or ileal sacs was measured after incubation for 30 min at 37 degrees C in pH 7.4 micellar solutions containing tritium-labeled oleic acid or tritium-labeled triolein. Lipids were extracted from homogenates of sacs and separated into lipid classes by thin layer chromatography. Equal amounts of oleic acid were taken up by jejunal or ileal sacs. Triolein uptake was less than oleic acid uptake, but uptakes by jejunal or ileal sacs did not differ. Oleic acid incorporation into triglyceride was three to four times greater in intestinal sacs from milk fat-fed calves than in sacs from calves fed either 3.5 or 7% tallow. Oleic acid incorporation in intestinal sacs from calves fed cholesterol as well as tallow was equal to that in milk fat-fed calves. Intestinal uptake and metabolism of oleic acid proceeded faster when calves were fed milk fat than when fed tallow. The lower intestinal incorporation with tallow increased if cholesterol was fed, suggesting that cholesterol either stimulated absorption or increased esterification.
Animals↗
Mastitis: effect of pH, temperature, and emollients on disinfecting action of N,N-dimethyldodecanamine.
Growth inhibition of bacteria over time by N,N-dimethyldodecanamine, a tertiary alkyl amine, was studied to evaluate disinfecting action with changes in pH and temperature and with addition of emollients. Because alkyl amines have limited solubility in aqueous solutions, the effect of pH on solubility of the tertiary amine was determined. Non-growing cultures of Streptococcus agalactiae or Escherichia coli were added to sterile buffer or buffer containing the amine, and at specific intervals aliquots were removed, neutralized in a lecithin/Tween 80 quencher, and then plated to determine the number of surviving bacteria per plate. Survival curves were used to determine the effect of changing environmental conditions on antimicrobial activity. Antimicrobial activity was greater at pH 7 than at pH 8 and was least at pH 6. Increases in temperature from 20 to 40 degrees C caused a corresponding increase in antimicrobial activity. Addition of up to 10% glycerin or propylene glycol caused no significant decrease in antimicrobial activity of the tertiary amine.
Amines↗
Effects of ronnel on growth, endocrine function and blood measurements in steers and rats.
Four feeding trials were conducted to determine (1) how the organophosphate ronnel affects thyroid and adrenal circulating hormone levels and blood profile measurements of beef steers and (2) whether the effects of ronnel observed in beef steers could be produced in growing rats. In trial 1, four groups of eight steers each were given either no ronnel or 4 mg ronnel/kg body weight daily in diets fed at either limited (1.8% of body weight) or ad libitum intake. After 7 weeks, intake levels, but not ronnel treatments, were reversed during a 1-week transition period, and feeding was continued for another 7 weeks. In trial 2, four groups of six steers each were given 0, 44, 88 or 176 ppm ronnel premixed in diets fed ad libitum for 18 weeks. Actual ronnel intakes averaged 0, 1.01, 2.12 and 4.73 mg/kg body weight daily in trial 2. In trials 3 and 4 , growth and intake were measured in 64 and 32 growing Sprague-Dawley rats, respectively, fed levels of ronnel ranging from 0 to 100 ppm in the diet. In trial 3, blood plasma was analyzed at various times for triiodothyronine (T3), thyroxine (T4), cholesterol and total lipid content. In trial 1, the concentration of Plasma T4 was 1.31 times higher in steers fed ronnel that in control steers. In trial 2, plasma T4 was 1.30 times higher in steers fed 176 ppm ronnel, the level that improved growth, than in steers fed the lower ronnel levels. Circulating levels of T3, cortisol and aldosterone were similar for both control and ronnel-fed steers. Serum cholesterol concentrations were consistently higher in ronnel-fed steers. The data indicated that the growth-promoting effect of ronnel in steers may be associated with a shift in thyroid function. Effects of ronnel in steers were not observed in rats, demonstrating a species difference between steers and rats.
Aldosterone↗
Effects of primary, secondary and tertiary amines on in vitro cellulose digestion and volatile fatty acid production by ruminal microorganisms.
Decanamine hydrochloride (a C10 primary amine), N-methylundecanamine (a C11 secondary amine) and N, N-dimethyldodecanamine (a C12 tertiary amine) were tested for their effects upon in vitro cellulose digestibility by unadapted ruminal microorganisms. The three amines exhibited similar patterns of inhibition of cellulose digestibility in 48-hr in vitro incubations. Cellulose digestion was depressed to 97, 89, 31, 11 and 12% of the control value by 5, 10, 25, 50 and 100 ppm of the amines, respectively. Total volatile fatty acid production was depressed to 89, 85, 61, 40 and 32% of the control value by 5, 10, 25, 50 and 100 ppm of the amines, respectively. Propionate production was inhibited to a greater extent than was acetate production, and acetate to propionate ratios increased in the presence of the amines. The results demonstrate that these primary, secondary and tertiary amines inhibit those microorganisms which digest cellulose in the rumen.
Amines↗
Effects of branched and straight chain amines and azasteroids on blood and egg cholesterol of White Leghorn chickens.
Six branched and straight chain secondary or tertiary amines with chain lengths of 12 to 18 carbons and two azasteroids, 25-aza-5 alpha-cholestane and 25-azacoprostane, were fed to mature White Leghorn hens, and their effectiveness was compared with 20,25-diazacholesterol dihydrochloride (SC-12937), an azasteroid known to lower egg cholesterol. Feed consumption, body weight, egg production, egg and plasma cholesterol and desmosterol, and plasma total lipid were measured. The 6 amines were fed at 200 ppm, and only the C12 branched chain amine N,N,3,711-pentamethyldodecanamine reduced plasma and egg cholesterol with a concomitant increase in desmosterol. After 4 weeks, plasma desmosterol was 0, 13, 60, and 75% of total sterol for control, 200 ppm C12 branched chain amine, 5 ppm diazacholesterol, and 5 ppm azacholestane, respectively. Egg production was severely reduced to 6 and 0% by feeding 5 ppm azacholestane for 2 and 4 weeks, respectively, and to 69 and 36% by feeding 5 ppm diazacholesterol. After 4 weeks egg cholesterol was 79 and 36% of the total sterol for the 200 ppm C12 branched chain amine and 5 ppm diazacholesterol, respectively. Concomitant increases in desmosterol accompanied all reductions in cholesterol. The depletion and repletion rates of egg cholesterol were measured in a subsequent experiment. After 2-1/2 weeks of feeding the test substances, egg cholesterol was reduced with concomitant increases in desmosterol. Egg cholesterol was 100, 71, and 50% of the total egg sterol for control, 200 ppm, and 400 ppm C12 branched chain amine, respectively: 58, 13, and 3% for .1, .5, and 1.0 ppm azacholestane; 28, 29, and 18% for 1, 2.5, and 5 ppm azacholesterol; and 23% for 1 ppm azacoprostane. The experimental diets were then withdrawn, and egg cholesterol repletion was studied biweekly. Egg cholesterol was repleted to 100% of the total sterol after withdrawal times of 2 weeks for C12 branched chain amine, 8 weeks for azacoprpostane, 14 to 16 weeks for diazacholesterol, 10 to 16 weeks for the lower levels of azacholestane, and longer than 16 weeks for 1 ppm azacholestane. The increase in desmosterol accompaning the demonstrated reduction in egg cholesterol, particularly with azasteroids, causes one to question the usefulness of this approach to lower cholesterol.
Amines↗
The effect of feeding Di-(2-ethylhexyl) phthalate (DEHP) on the lipid metabolism of laying hens.
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Animals↗
Mastitis: II. Evaluation of antimicrobial amines for use as teat dips.
Recent proposals by the Food and Drug Administration to regulate teat dips as drugs have led to a search for safer teat dip ingredients. Primary, secondary, and tertiary alkyl amines (carbon-10 to -18 chain length) inhibit growth of mastitic bacteria (Streptococcus agalactiae, Streptococcus uberis, Staphylococcus aureus, Escherichi coli, Klebsiella pneumoniae) in a broth tube culture assay. Since carbon-13 compounds were active, a carbon-13 primary (tridecanamine hydrochloride), secondary methyl (N-methyltridecanamine), secondary ethyl (N-ethyltridecanamine), tertiary dimethyl amine (N, N-dimethyltridecanamine), and carbon-12 quaternary amine (N, N, -trimethyldodecaneammonium chloride) were tested for their ability to reduce experimentally applied populations of S. agalactiae or E. coli on the bovine teat surface. The five compounds were compared at concentrations of 100, 500, 1,000, 3,000, 7,000, and 10,000 ppm. Activity was greater against the gram-positive S. agalactiae than against the gram-negative E. coli. The tertiary amine was most active, producing a log reduction of 4 (reduction of bacterial number from 10(6) to 10(2)) at a concentration of 3,000 ppm in the teat dip. The relative order of effectiveness for the amines was: dimethyl tertiary greater than methyl secondary greater than ethyl secondary greater than primary = quaternary. The results suggest that these amines may be useful as potent, effective antibacterial agents for incorporation into teat dips.
Amines↗