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Biomedical subjects

J Bitman

Publications and source records attributed to J Bitman.

At least 19 recordsLinked to original sources
PubMed1992

Human milk in disease: lipid composition.

Differences in the lipid composition of human milk have been described in maternal diseases known to affect fat metabolism. Diseases such as diabetes, cystic fibrosis, hypobetalipoproteinemia and Type I hyperlipoproteinemia affect the quantity and quality of human milk fat. Increased fatty acid chain elongation and changes in desaturation (especially delta 6 desaturase), as well as changes in lipid class composition, have been shown in diabetes and cystic fibrosis, whereas compensatory increases in medium-chain fatty acids have been described in hypobetalipoproteinemia and Type I hyperlipoproteinemia. It is important to realize that these observations were made either on single women or on very small groups of women. In infant diseases, such as breast milk jaundice and ectopic eczema, changes in polyunsaturated fatty acids in maternal milk have been described.

Cystic Fibrosis↗
PubMed1992

Human mammary gland function at the onset of lactation: medium-chain fatty acid synthesis.

The onset of medium-chain fatty acid synthesis in the human mammary gland was investigated. Colostrum and serum were collected from 31 healthy women and the fatty acid composition of total lipid was analyzed by gas-liquid chromatography. Although colostrum/serum ratios for most fatty acids range from 0.7-2.4, very low levels of 10:0 and 12:0 were present in serum lipids as compared to much higher concentrations of these fatty acids in colostrum lipids (colostrum/serum ratio 16.23 and 17.11 for 10:0 and 12:0, respectively). We have previously found that medium-chain fatty acid levels are very low in prepartum mammary secretions (6-10 wk before term delivery) but are higher and similar in colostrum of women who deliver preterm (3-14 wk) or at full term. The data indicate that parturition, irrespective of length of pregnancy, is the trigger for medium-chain fatty acid synthesis in the human mammary gland.

Breast↗
PubMed1992

Milk and blood fatty acid composition during two lactations in the same woman.

Fatty acid composition of colostrum, milk, and serum was studied during two consecutive lactations in the same woman. There were marked differences between milk and serum: medium chain fatty acids (C6:0-C14:0) were higher in milk (8.36-21.37%) than in serum (1.59-9.6%) throughout lactation. The high milk-serum ratio of medium chain fatty acids (up to 28.4, 30.2, and 6.2 for 10:0, 12:0, and 14:0, respectively) indicates synthesis in the mammary gland. Long-chain polyunsaturated fatty acids (C20:1-C22:6) of the n - 3 and n - 6 series were higher in serum (6.76-12.53%) than in milk (1.57-4.42%). With the exception of colostrum, the fatty acid composition of milk and serum changed little during lactation and was similar in two consecutive lactations in the same woman. Comparison of milk and serum fatty acids provides a noninvasive approach for the assessment of the synthetic activity of the human mammary gland.

Adult↗
PubMed1992

Changes in the lipid composition of the secretions of the bovine mammary gland during the dry period.

To study initiation of milk fat synthesis, lipid composition of mammary secretions at -60, -40, and -10 d prepartum was studied in lactating and nonlactating Holstein cows. Eleven cows were dried off, and 13 cows were milked twice per day throughout the normal dry period. Total neutral lipid was similar in late lactation milk (-60 d) from lactating cows, 2.1 g/dl, and in milk from the dry group, 2.2 g/dl. Neutral lipids decreased to 1.3 and .9 g/dl in quarters from dry cows at -40 and -10 d prepartum. In secretions from dry quarters, triglycerides were 97% of total lipids at -60 d and decreased to 85 and 91% at -40 and -10 d, respectively. Conversely, FFA and monoglycerides increased during the dry period. Lipids associated with fat globule membrane components increased during the dry period. These increases were 10 times for cholesterol, 20 times for cholesteryl esters, and twice for phospholipids. In general, the content of fat globule core lipids (triglycerides) exhibited a pattern opposite that of membrane lipids (cholesterol, cholesteryl esters, phospholipids) during the prepartum period. Proportions of core lipids tended to decrease, whereas proportions of membrane lipids increased in prepartum mammary secretions. Lipid composition of prepartum secretions may be influenced by blood lipids, somatic cells, and alterations in mammary lipid synthesis.

Animals↗
PubMed1992

Effect of clinical and subclinical mastitis on lipid composition of teat canal keratin.

Two experiments were conducted to investigate lipid composition of teat canal keratin when different conditions of bacterial colonization and quarter inflammation were present. In Experiment 1, 11 multiparous cows with subclinical mastitis (bacteria present but no visible inflammation) in at least one quarter were selected for study. Quarters that were sampled and found negative for bacterial growth were classified as control. In Experiment 2, 10 multiparous cows with clinical mastitis in one or more quarters were selected. Milk samples from inflamed quarters were cultured to identify mastitis pathogens; these quarters were classified as clinical; all other quarters were classified as control. Teat canal keratin was collected from all quarters just before an a.m. milking, samples were weighed, and lipid determinations were conducted by TLC. Keratin from subclinical quarters compared with keratin from control quarters did not differ in either neutral lipid or fatty acid composition. Total lipid was significantly higher in keratin from teats of clinical quarters than in keratin from control quarters (27.8 vs. 21.5 microgram/mg). Neutral lipid composition of keratin was similar between teats from clinical quarters and teats from control quarters. In Experiment 2, quarter foremilk samples were also obtained to determine lipid composition. The FFA in milk from clinical quarters contained fewer short-chain fatty acids, whereas polyunsaturated fatty acids were significantly higher in milk from clinical quarters.

Animals↗
PubMed1992

Increased susceptibility to intramammary infection following removal of teat canal keratin.

Influence of teat canal keratin on susceptibility to intramammary infection was investigated in lactating Jersey cows. In each of two replicate trials, keratin was removed from the left teats of 20 cows immediately before milking. Immediately after milking, all teats were exposed to bacterial challenge by immersion in a suspension of Streptococcus agalactiae (5 x 10(7) cfu/ml). Bacterial challenge was repeated after the next four milkings. Foremilk samples were obtained for 8 d after keratin removal to determine infection status. A mammary quarter was classified as infected based solely upon the bacteriological criteria outlined by the National Mastitis Council. The rate of infection in quarters from which keratin was removed was greater than that in control quarters. Infection rates were 26.3% for keratin-removed quarters and 8.3% for control quarters in trial 1 and 13.5 and 0%, respectively, in trial 2. When more stringent criteria (recovery of greater than 100 cfu of S. agalactiae/ml in three or more successive milk samples and a SCC of greater than 10(6)) were used to identify a subset of infections that were clearly intramammary, infection rates were 9.3% for keratin-removed quarters and 1.4% for control quarters. Thus, partial removal of keratin from the teat canal compromised the ability of the teat to prevent passage of bacterial pathogens from the external environment into the mammary gland.

Animals↗
PubMed1979

Stimulation of lipid absorption in young rats by cholesterol: early time changes and effects on pentobarbital sleeping time.

Four groups of young male and female rats were fed a chow diet (O), chow plus 10% corn oil (F), chow plus 1% cholesterol (C), or chow plus 1% cholesterol plus 10% corn oil (CF) for 1, 2, 4 and 8 days. After 2 dats, male F, C and CF rats exhibited a shorter anesthesia period (-20 to -30%) when given pentobarbital. By 4 days, male F and C rats had pentobarbital sleeping times (PB-ST) 20% less than O rats. These effects were additive and CF rats had 40% shorter PB-ST. Reduction of PB-ST by cholesterol and corn oil was similar but slightly less in female rats. Liver lipid content doubled in 4 days in CF rats, and liver cholesterol was 4 times than of O rats. These changes and the increases in metabolism of barbiturate suggested changes in liver microsomal enzyme activities. Serum glutamic oxaloacetic and glutamic pyruvic transaminase, two enzymes reflective of liver damage, did not increase after 8 days on C, F or CF diets. Our results suggest that consumption of an animal sterol and a high lipid diet by laboratory rats, normally consuming a diet low in fat (3-4%), increase the ability of the animal to detoxify a barbiturate. Storage of absorbed dietary cholesterol in the liver may represent a major mechanism for maintaining extra hepatic cholesterol homeostasis.

Absorption↗
PubMed1979

Mastitis: I. In vitro antimicrobial activity of alkyl amines against mastitic bacteria.

The activities of branched and straight chain amines (10 to 18 carbons chain length) were compared in inhibiting the growth of five microorganisms that cause about 95% of bovine mastitis. Three gram-positive (Streptococcus agalactiae, Streptococcus uberis, Staphylococcus aureus) and two gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria were used in a trypticase soy broth tube culture growth assay. Sixty-two compounds were screened at concentrations of 200, 100, 50, 25, 10, 5, and 1 ppm in broth culture to determine the effective minimum inhibitory concentration. Alkyl secondary N-substituted monoethyl [CH3(CH2)nNHCH2CH3] and tertiary N,N-substituted dimethyl [CH3(CH2) nN(CH3)2] amines with chain lengths of 11 to 14 carbon atoms were active against both gram-positive and gram-negative organisms. Antimicrobial activity against gram-positive organisms increased with increasing chain length and carbon-14 to 18 amines were active at 1 to 5 ppm. The carbon-11 to 13 alkyl amines were most active against gram-positive organisms; longer chain amines (more than 14 carbons) were inactive. Branching of the alkyl chain caused a loss of activity against gram-negative but not against gram-positive bacteria. Antimicrobial testing of monoamines, polyamines, and the influence of order substituents were investigated to correlate structure-acitivity relationships.

Amines↗
PubMed1979

Feeding cholesterol and tallow to young calves.

Four groups of eight 4 wk-old Holstein bull calves were fed calf starter diets containing either no additive (control) or added ingredients: 1% cholesterol, 5% tallow, or 1% cholesterol plus 5% tallow. Body weight and size were reduced, and average daily gain was lowered by added 5% tallow. The added dietary tallow and cholesterol increased lipids and cholesterol of plasma by 35 to 40%. The increased intake of fat due to feeding tallow caused both increased fat metabolism and fat excretion as based on chromic oxide estimates of digestibility. Fat digestibility was lowest in animals receiving cholesterol with no added tallow. Organ weights and composition of meat at slaughter at 21 wk of age were not different.

Animal Feed↗
PubMed1978

Liver mixed function oxidases in chickens: induction by polychlorinated biphenyls and lack of induction by DDT.

Microsomal hydroxylase and demethylase activities were compared in livers from White Leghorn cockerels fed polychlorinated biphenyls (PCBs) containing 21 to 68% chlorine, or p,p'-DDT. The higher chlorinated PCBs, Aroclor 1254 and 1268, were potent inducers of hepatic enzyme activity while DDT did not induce these enzymes. Aroclor 1254 was the most potent inducer because feeding 5 ppm increased liver aminopyrine demethylase activity 1.5X but did not affect liver weight. Feeding 50 and 500 ppm of Aroclor 1254 and 1268 increased liver weight and demethylase activity per mg of protein. A differential response in the two enzymes occurred. Only 500 ppm of Aroclor 1268 increased hydroxylase activity. Aroclor 1242 had no effect on liver enzyme concentration but 50 and 500 ppm of Aroclor 1242 increased liver weights and consequently increased total enzyme activity. Our data demonstrated that in the avian species DDT and PCB did not have the same effect on hepatic microsomal enzyme activity.

Aniline Hydroxylase↗
PubMed1978

Necessity of vitamin B12 for growth of rats fed on an odd- or even-carbon-number fat.

1. The effect of vitamin B12 on growth was studied in young male and female rats fed on diets sufficient (+B12) or deficient (-B12) in vitamin B12 containing 30% of the dietary energy as fat, either maize oil (CO) or triundecanoin (TUD). 2. Vitamin B12 deficiency severely depressed growth. After 6 weeks the weight gain of CO(-B12) rats was only 72% of that of CO(+B12) rats and the gain of TUD(-B12) rats was only 47% of TUD(+B12) rats. 3. After fasting 24 or 96 h TUD-fed rats, both +B12 and -B12, had greater glycogen reserves and higher plasma glucose levels than CO-fed rats. 4. It is concluded that vitamin B12 is required for the metabolism and utilization of both an odd-carbon-number medium-chain fat, TUD, and an even-C-number long-chain fat, CO, during growth in rats.

Animals↗
PubMed1978

Embryotoxic effects of polybrominated biphenyls (PBB) in rats.

Pregnant Sprague Dawley rats were given 0, 0.25, 0.5, 1, 5, and 10 mg of a commercial polybrominated biphenyl, FireMaster BP-6 (PBB), in olive oil by gavage each day from days 7 through 15 of pregnancy. Laboratory chow and water were given ad libitum. Treatment with PBB had no significant effect on body weight gain, food and water consumption, and urine production. The mothers were killed on day 20, and the only significant effect observed was an increased liver weight of those given 1, 5, and 10 mg PBB. Spleen, kidney, ovarian, gravid uterine, and perirenal fat pad weights were similar to those of control mothers. PBB had no significant effect on number of live/dead fetuses, crown-rump length or fetal weight. No grossly malformed fetuses were observed in PBB-treated mothers. The effects of PBB transfer from mothers to nursing pups was studied by reciprocal exchange of pups between control mothers and mothers treated with 10 mg PBB. When the pups were 21 days old, they were weaned and fed control chow. The following four combinations of prenatal-postnatal exposure were studied: control-control (C:C); control-PBB (C:PBB); PBB-control (PBB:C); and PBB-PBB. Although the birth weights of pups from PBB-treated mothers were similar to those of the controls, body weights of 60-day-old males exposed prenatally and postnatally (PBB:C, C:PBB, and PBB:PBB) were less (p less than 0.05) than those of the controls (C:C). The weights of the perirenal fat pads of male and female pups exposed to PBB were less (p less than 0.05) than the control. Liver weights, on a body weight basis, were higher in male and female pups exposed to PBB. Vaginal openings were delayed; the percentages of 36-day-old pups with open vaginas were 50 (C:C), 38 (PBB:C), 28 (C:PBB), and 30 (PBB:PBB).

Animals↗
PubMed1977

Milk and tissue lipid composition after feeding cows protected polyunsaturated fat for two years.

The long-term effects of feeding Holstein cows plant lipids protected from microbial hydrogenation in the rumen were studied. Of particular interest were cow health and changes in fatty acid and cholesterol concentrations of milk and meat. Safflower oil-casein or safflower oil-casein treated with formaldehyde to impede microbial attack were fed to two groups of three cows as 10% of the concentrate ration for two lactations. Production of milk fat of cows fed the protected concentrate increased significantly. Linoleic acid of milk fat was twice normal, providing a polyunsaturated milk. Cholesterol of milk or meat did not increase even though cholesterol of blood plasma was higher in both groups fed safflower oil than in control cows. Cardiovascular systems showed no marked abnormalities and no differences that could be due to treatment. All cows maintained normal health and milk production throughout the experiment.

Animals↗