Guinea pig mammary gland milk content by isotope dilution methods using 141 Ce and 14 C-polyethylene glycol-4000

The use of ¹⁴¹Ce and ¹⁴C-polyethylene glycol-4000 (¹⁴C-PEG) as contained-milk volume indicator labels was tested in the guinea pig mammary gland. Labels in aqueous solution were introduced into the mammary gland, the gland was manipulated periodically during a waiting period, and then samples of milk were serially drawn from the glands with the aid of oxytocin. Neither label penetrated uniformly into all milk compartments. A portion (approximately 10%) of the ¹⁴C-PEG was absorbed during the experimental time of 90 to 115 min and precluded its use as a dilution indicator label in the guinea pig. Ninety eight percent of the ¹⁴¹Ce was recovered from the gland; however, its nonuniform distribution produced an underestimate of the contained-milk volume. A method is described whereby the initial underestimate of milk volume can be corrected. The method is based on a sample of milk taken under conditions of nonuniform dispersion of ¹⁴¹Ce and an estimate of the deviation of the ratio (% of initial milk estimate)/(% of accumulated dose) for total milk from the theoretical value of 1. By this method, ¹⁴¹Ce can yield reliable estimates of the contained-milk content of the guinea pig mammary gland.     

Inhibiting prolactin by cabergoline accelerates mammary gland remodeling during the early dry period in dairy cows

The inhibition of prolactin release using cabergoline, a dopamine agonist, is an effective strategy to accelerate the changes in mammary secretion composition after drying-off. The objective of this study was to determine how cabergoline may affect mammary tissue remodeling during early involution. Holstein dairy cows were treated with either a single i.m. administration of 5.6 mg of cabergoline (Velactis, Ceva Santé Animale, Libourne, France, n = 7) or placebo (n = 7) at the time of drying-off. Mammary biopsy samples were collected 1 wk before drying-off (d ?6), after 30 h of milk accumulation (d 1), and again 8 d following drying-off (d 8) to determine changes in gene expression, lactoferrin content, and cell turnover. Blood and mammary secretion samples were collected at d ?6 and again at d 1, 2, 3, 4, 8, and 14 following the abrupt cessation of lactation to evaluate indicators of blood-milk barrier integrity and other markers of mammary tissue remodeling. Cabergoline induced less SLC2A1, BAX, CAPN2, and IGFBP5 mRNA expression. In contrast, cabergoline did not modify changes in cell proliferation and apoptosis. Following the cessation of lactation, changes in mammary secretion composition (Na⁺ and K⁺) and blood lactose concentrations were indicative of a loss in the blood-milk barrier function in both treatment groups. Cabergoline treatment affected only Na⁺ and K⁺ concentrations at d 1, suggesting a moderate increase in tight junction permeability. The increase in the activity of MMP9 and in mammary epithelial cell concentration in mammary secretions was greater in cabergoline-treated cows than in control cows, suggesting more mammary tissue remodeling. The increase in lactoferrin immunostaining in the mammary tissue occurred earlier for cabergoline-treated cows than for control cows, and was essentially localized in the stroma. Changes in some key markers of mammary involution suggest that cabergoline accelerates mammary gland remodeling. Thus, a single injection of cabergoline after the last milking would facilitate drying-off by enhancing mammary gland involution.     

The removal of soluble organic carbon from synthetic winery wastewater by repeated application to soil

The removal of soluble organic carbon from synthetic winery wastewater containing uniformly ¹⁴Clabelled lactic acid and glycerol applied repeatedly to soils sampled at various depths from a brown earth and solod was determined from decreases in the solution concentration of ¹⁴C of soil extracts. A previously developed logistic model was used to quantify the adsorption and microbial metabolism of the ¹⁴C-compounds in the various soil layers. Adsorption of ¹⁴C-compounds to soil particles resulted in the removal of 10 to 50% of the added ¹⁴C within the first hour after wastewater application. It was greater in soils containing a higher percentage of clay and/or organic carbon. Repeating wastewater applications up to 17 times reduced initial adsorption by most of the soil layers of the brown earth, whereas little change occurred in the solod. Microbial uptake and metabolism were responsible for the removal of ¹⁴C-compounds remaining in solution to less than 5% of ¹⁴C input. In contrast with their effect on adsorption, repeated applications of wastewater decreased or eliminated the lag period before the onset of rapid metabolism and also increased the rates of metabolism of ¹⁴C-compounds in all soils. This led to significant reductions in the removal times of the soluble-¹⁴C. Acclimatisation of microbial populations in soils newly exposed to the wastewater was most rapid within the uppermost layers. Acclimatised soils were able to reduce the solution concentration of ¹⁴C to less than 5% of input levels within 1 d after application when the lag period lasted less than 2 h, and when the daily removal of solution-¹⁴C, due to microbial metabolism, exceeded the ¹⁴C input. Regular applications of wastewater were required to maintain rapid removal of the soluble-¹⁴C in acclimatised soils. Implications for managing the disposal of wastewaters rich in organic material on new and existing sites are discussed.     

Effect of sunflower-seed oil and linseed oil on tissue lipid metabolism, gene expression, and milk fatty acid secretion in Alpine goats fed maize silage–based diets

Lipid in the diet is known to enhance milk fat secretion and alter milk fatty acid composition in lactating goats. In the current experiment, the contribution of peripheral tissue and mammary gland lipid metabolism to changes in milk fat composition from plant oils was examined. Fourteen Alpine goats in midlactation were used in a 3 × 3 Latin square design with 28-d experimental periods. Treatments comprised maize silage–based diets containing no additional oil (M), sunflower-seed oil (MSO; 6.1% of diet DM), or linseed oil (MLO; 6.2% of diet DM). Compared with the control, milk yield was greater in goats fed MSO (3.37 and 3.62 kg/d, respectively), whereas MLO enhanced milk fat content (+3.9 g/kg), resulting in a 14% increase in milk fat secretion. Both MSO and MLO increased milk lactose secretion by 12 and 8%, respectively, compared with M. Relative to the control, plant oils decreased C10 to C16 secretion (32 and 24%, respectively, for MSO and MLO) and enhanced C18 output in milk (ca. 110%). Diets MSO and MLO increased cis-9 18:1 secretion in milk by 25 and 31%, respectively, compared with M. The outputs of trans-11 18:1 and cis-9, trans-11 18:2 in milk were increased 8.34- and 6.02-fold for MSO and 5.58- and 3.71-fold for MLO compared with M, and MSO increased trans-10 18:1 and trans-10, cis-12 18:2 secretion. Plant oils decreased milk fat cis-9 14:1/14:0; cis-9 16:1/16:0; cis-9 18:1/18:0; and cis-9, trans-11 18:2/trans-11 18:1 concentration ratios but had no effect on mammary stearoyl-CoA desaturase mRNA or activity. Furthermore, changes in milk fatty acid secretion were not associated with alterations in mammary acetyl-CoA carboxylase mRNA and activity, abundance of mRNA encoding for lipoprotein lipase and fatty acid synthase, or malic enzyme and glycerol-3-phosphate dehydrogenase activity in mammary tissue. Mammary lipoprotein lipase activity was increased with MSO relative to MLO. Treatments had no effect on glucose-6-phosphate dehydrogenase, malic enzyme, glycerol-3-phosphate dehydrogenase activity, or mRNA abundance and/or activity of lipoprotein lipase, acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase in liver or adipose tissue. In conclusion, inclusion of sunflower-seed oil and linseed oil in maize silage–based diets alters milk fatty acid secretion in goats via mechanisms independent of changes in mammary, hepatic, or adipose tissue lipogenic gene expression. Furthermore, data provided indications that the regulation of mammary lipogenic responses to plant oils on starch-rich diets differs between the caprine and bovine.     

The role of sebum and epidermal lipids in the cosmetic properties of skin

Lipids found in the skin are derived both from the keratinized epidermis and from the sebaceous glands. The composition of human sebum and epidermal lipids has only been fully elucidated during the past few years, and the role of these lipids is still being evaluated. This presentation reviews sebaceous gland structure and function composition of human sebum, the effects of aging and hormones on sebum secretion and the role of sebum in acne and in dry skin. In addition, a review of the role of epidermal lipids in the properties of skin includes consideration of the structure and function of the epidermis, the composition of the epidermal lipids, and the function of lipids in epidermal differentia-tion and water barrier properties.
Le rle du sébum et des lipides de I'épiderme dans les propriétes cosmétiques de la peau     

In vivo breakdown of dietary [methyl−14C] and [uronate-6−14C]pectin-labelled spinach cell walls by rat intestinal microorganisms and incorporation of 14C into host tissues

The metabolism of dietary plant cell wall (PCW) pectin was followed in the rat using PCW isolated from spinach cell cultures ¹⁴C-labelled in the galacturonic acid residues or pectic methyl ester groups. ¹⁴C-PCW were rapidly broken down in the caecum and colon of the rat and generated several groups of soluble products. [¹⁴C]Methanol was released from [methyl^?14C]pectin-labelled PCW and some of the methanol was converted to ¹⁴C-labelled volatile acids. ¹⁴C-Labelled volatile acids were also generated from [uronate-6-¹⁴C]pectin-labelled PCW along with soluble but non-volatile material. ¹⁴C derived from both cell wall types was taken up by the caecal and colonic mucosa and transported to the liver, pelt and other body tissues. Some ¹⁴C was excreted as ¹⁴CO₂ and in urine.     

Effect of casein and propionate supply on mammary protein metabolism in lactating dairy cows

The effects of casein (CN) and propionate (C3) on mammary AA metabolism were determined in 3 multiparous Holstein cows fitted with both duodenal and ruminal cannulas and used in a replicated Youden square with six 14-d periods. Casein (743 g/d in the duodenum) and C3 (1,041 g/d in the rumen) infusions were tested in a factorial arrangement. For each period, l-[1-¹³C]Leu (d 11) and NaH[¹³C]O₃ (d 13) were infused into a jugular vein, and blood samples were taken from the carotid artery and the mammary vein to determine Leu kinetics and net uptake of AA. Both CN and C3 treatments separately increased milk protein concentration and yield. With CN there was a general response in mammary protein metabolism, involving increases in Leu net uptake (30%), the uptake:output ratio (8%), protein synthesis (11%), secretion in milk protein (21%), and oxidation (259%). In contrast, C3 treatments tended to increase only Leu in milk protein (7%) and, when in combination with CN, to reduce Leu used for protein synthesis (5%). Across all treatments, most Leu uptake by the mammary gland was accounted for as Leu in milk or oxidized, and the Leu balance was therefore achieved without involvement of either net peptide use or production. Mammary uptake of group 1 AA increased to match milk output with all infusions. In contrast, mammary uptake of group 2 AA exceeded output to a greater extent with CN than with C3 infusions, whereas the increment in uptake of group 3 AA increased with C3 treatments. Overall, these data suggest that different mechanisms operate to improve milk protein production when either protein or energy is supplied.     

Metabolism and fate of dietary (U-14C)-labelled spinach cell walls in the rat

Using uniformly ¹⁴C-labelled spinach (Spinacia oleracea L) plant cell walls (PCW) the metabolism of PCW can be followed in a defined manner in the rat. Only 10% of the ¹⁴C was recoverable in the gut contents and faeces 18 h post-gavage. Two percent of the ¹⁴C was excreted in urine and 25% excreted as CO₂. ¹⁴C was found in all tissues of the body but was most concentrated in the adrenal glands, colon and caecum. The ¹⁴C was also present at moderately high concentration in the liver pelt, and owing to their larger size, these tissues accounted for a high percentage of the total ¹⁴C. In the liver the ¹⁴C was predominantly associated with phospholipid, whereas in the pelt it was present in protein and in fatty acid residues esterified to cholesterol. Dietary PCW material is extensively fermented in the caecum and colon. Also, the products of fermentation are a source of energy and important structural precursors of lipids and proteins for the animal.     

Degradation and metabolism of 14C‐labelled proanthocyanidins from carob (Ceratonia siliqua) pods in the gastrointestinal tract of the rat

The aim of the work was to study the binding, degradation and metabolism of dietary condensed tannins in the gastrointestinal tract of an omnivore. Young pods of carob (Ceratonia siliqua L) were radiolabelled by in vivo feeding of ¹⁴CO₂, trans‐[U‐¹⁴C]cinnamate or L ‐[U‐¹⁴C]phenylalanine. [¹⁴C]Proanthocyanidins (condensed tannins) were extracted with acetone/water (3:1 v/v), isolated on Sephadex LH‐20 and fed to rats by gavage. After 4 and 18 h, 90–94% of the gavaged ¹⁴C was in the gut contents and/or faeces. Much of the gavaged ¹⁴C (57%), predominantly that originally in tannins of high degree of polymerisation (DP), became insolubilised, mainly in the form of protein–tannin complexes. Some of the [¹⁴C]tannins that remained soluble decreased in DP, especially in the small intestine and caecum. A further fraction (12% of the ¹⁴C gavaged) underwent chemical modifications in the gut to form soluble, non‐tannin compounds. Small proportions of the ¹⁴C were found in the liver (1.0–1.5%), urine (1–2%) and ¹⁴CO₂ (1–2%). We conclude that proanthocyanidins are not inert within the gut but undergo various modifications which may affect the nutrition of the animal. © 2001 Society of Chemical Industry     

Hair lipid and surfactants. Extraction of lipid by surfactants and lack of effect of shampooing on rate of re-fatting of hair

The efficiences of extraction of hair lipid by aqueous solutions of surfactants, using a one-stage washing procedure, are highly variable, roughly averaging 50% of the lipid readily extractable with diethyl ether at room temperature. Anionic surfactants are significantly more efficient than the non-ionic surfactant, Tween 20^R. Repeated washing of hair continually removes lipid. It is suggested that a one-stage washing procedure removes essentially all the hair-surface lipids and that differences in cleaning efficiences of surfactants reflect differences in the amounts of internal hair lipid eluted. Variation of the frequency of shampooing from once to three times weekly had no significant effect on the rate of re-fatting of hair when two anionic surfactants in commercial shampoo formulations were investigated, i.e. no evidence was obtained in support of either the hypothesis for a feedback mechanism for control of the level of hair lipid, or the suggestion that surfactants can directly stimulate sebaceous gland activity. Lipides du cheveu et surfactants-extraction des lipides par les surfactants et absence d'effet des shampooings sur le taux de regraissage du cheveu     

Nutritional Properties and Metabolic Studies of Acylated Beef Heart Myofibrillar Proteins

Beef heart myofibrils were acylated with several concentrations of acetic (AA) and succinic (SA) anhydride, and digestibility and utilization of the myofibrillar proteins were determined. Results for in vitro hydrolysis of the untreated and acylated proteins varied, depending on the enzyme(s) used in the analysis. Rat protein efficiency ratios and net protein ratios for untreated (PER = 2.83, NPR = 116) and acetylked (PER = 2.55, NPR = 110) proteins were greater than for casein (PER = 2.50, NPR = 100), whereas values for succinylated proteins (PER = 2.36, NPR = 87) were less than for casein. Most of the radioactivity recovered after 24 hr from rats fed ¹⁴C-acylated myofibrillar proteins was in expired CO₂; 62.8% for ¹⁴C-acetylated and 45.8% for ¹⁴C-succinylated proteins. Rats acclimated to an acylated protein diet for 28 days showed improved metabolism of ¹⁴C-acetylated protein and decreased metabolism of ¹⁴C-succinylated proteins; 75.7% and 38.1% recovery as expired CO₂, respectively.     

Short communication: Temporal changes in the skin morphology of dairy cows during the periparturient period

Management of dairy cow productivity requires monitoring of their nutritional status by visual observation. It has been suggested that changes in hair coat appearance are among the indicators of nutritional state in dairy cows. Temporal changes in the skin morphology in cows, however, have not been reported. In this study, we examined the changes in the skin of dairy cows that occur during the peripartum period. Seven pluriparous cows were used. Skin samples were collected at 28 d before the due date and 28 d and 56 d after calving for morphological examination. Hair follicle width was 108.8 ± 5.9 µm (±SD) in the dry period, 95.5 ± 5.5 µm at 28 d after calving, and 104.2 ± 5.3 µm at 56 d postpartum. The percentages of anagen hair follicles during these 3 periods were 41.4 ± 3.4, 18.5 ± 3.4, and 32.3 ± 3.3%, respectively. The corresponding sebaceous gland sizes were 8,362.0 ± 707.6, 7,800.0 ± 831.4, and 9,186.8 ± 962.6 µm², respectively. Hair follicle width was positively correlated with percentage of anagen hair follicles. The thickness of epidermal and proliferation rate of epidermal cell were also correlated. However, the hair follicle width, sebaceous gland size and cell proliferation rate, and thickness and proliferation rate of epidermal cells did not show any marked changes.     

Changes in the expression of α-tocopherol-related genes in liver and mammary gland biopsy specimens of peripartum dairy cows

Blood α-tocopherol (α-Toc) concentrations decline gradually throughout the prepartum period, reaching the nadir after calving in dairy cows. The 6 α-Toc–related molecules [α-Toc transfer protein (TTPA); afamin; scavenger receptor class B, Type I; ATP-binding cassette transporter A1; tocopherol-associated protein (SEC14L2); and cytochrome P450 family 4, subfamily F, polypeptide 2 (CYP4F2)] are expressed in liver and other peripheral tissues. These molecules could regulate α-Toc transport, blood concentrations, and metabolism of α-Toc. Therefore, the aim of this study was to evaluate the changes in the expression of α-Toc–related genes in liver and mammary gland tissues of dairy cows around calving, which have remained elusive until now. In experiment (Exp.) 1, 28 multiparous Holstein cows were used (from ?5 to 6 wk relative to parturition) to monitor the changes in dietary α-Toc intake, blood concentrations of α-Toc, and lipoproteins; in Exp. 2, 7 peripartum Holstein cows were used (from ?4 to 4 wk relative to parturition) for liver tissue biopsy; and in Exp. 3, 10 peripartum Holstein cows were used (from ?8 to 6 wk relative to parturition) to carry out the mammary gland tissue biopsy and milk sampling. In Exp. 1, the serum α-Toc concentrations declined gradually with decreasing amount of α-Toc intake and plasma high-density lipoprotein concentrations toward calving time. However, in the early lactation period after calving, serum α-Toc concentrations remained at a lower concentration despite the recovery of α-Toc intake and plasma high-density lipoprotein concentrations. In Exp. 2, just after calving, the TTPA, SEC14L2, afamin, and albumin mRNA expression levels in the liver were temporarily downregulated, and the hepatic mRNA levels of endoplasmic reticulum stress-induced unfolded protein response markers and acute-phase response marker increased at calving. In Exp. 3, the concentrations of α-Toc in colostrum were greater than those in precolostrum (samples were collected at wk ?1 relative to parturition) and mature milk. The expression of TTPA, SEC14L2, and CYP4F2 mRNA in bovine mammary gland tissue was detected. However, TTPA and SEC14L2 mRNA expressions showed the opposite trends: the expression levels of TTPA mRNA peaked whereas SEC14L2 mRNA reached a nadir at calving. These results indicate that the expression of α-Toc–related genes involved in specific α-Toc transfer and metabolism in the liver and mammary gland are altered during calving. Moreover, these changes might be associated with the maintenance of lower serum α-Toc concentrations after calving.     

Endogenous synthesis of milk oleic acid in dairy ewes: In vivo measurement using 13C-labeled stearic acid

The use of stable isotopes is a reliable and risk-free alternative to radioactive tracers for directly examining in vivo fatty acid (FA) metabolism. However, very limited information is available in ruminants, and none is available in sheep. Therefore, we conducted an experiment in dairy ewes to determine, for the first time in this species, the uptake, Δ⁹-desaturation, and secretion of ¹³C-labeled stearic acid (SA) into milk with the aim of measuring in vivo endogenous synthesis of milk oleic acid (OA) and stearoyl-CoA desaturase activity. Six lactating Assaf ewes fed a total mixed ration (forage:concentrate ratio = 30:70) received an intravenous injection of 2 g of ¹³C-labeled SA. At ?24, ?15, 0, 4, 8, 12, 16, 20, 24, 36, 48, 60, and 72 h postinjection (p.i.), milk yield was recorded and milk samples were collected to examine fat concentration and FA composition, including compound-specific isotope analysis of SA and OA by gas chromatography–combustion isotope ratio mass spectrometry. Over the p.i. period, the SA proportion ranged from 7.6 to 8.3% of total FA, with a maximum ¹³C enrichment of 1.9%, whereas OA was more abundant (14.3–15.4% of total FA) and had lower ¹³C enrichments (up to 0.69%). On average, 15% of the isotopic tracer was transferred to milk within 72 h p.i., and 47 to 50% of the SA taken up by the mammary gland would have been desaturated to OA. The proportion of oleic acid being synthesized endogenously was estimated to represent between 48 and 57% of the amount secreted in milk. Further research under different dietary conditions is recommended.     

Lysine metabolism by the mammary gland of lactating goats at two stages of lactation

An arteriovenous kinetics technique was used to monitor mammary gland lysine and protein metabolism in goats (n = 4) at two stages of lactation (80 +/- 17 vs. 233 +/- 14 DIM) in response to an i.v. infusion of lysine (Lys) plus methionine (Met). At each stage of lactation [2-15N] and [1-13C; 6,6-2H2] Lys kinetics were performed on the last day of 5-d i.v. infusion of saline followed by Lys (370 mg/h) plus Met (84 mg/h, LM). Milk and protein yields and dry matter intake were higher in early than in late lactation, but LM infusion did not affect these variables. Regardless of stage of lactation, the absolute and fractional oxidation rates of Lys by the mammary gland increased in response to LM infusion. When corrected for Lys oxidation, net uptake of Lys by the gland was less than milk protein Lys secretion. However, correction for the contribution of peptides (15.8%) to Lys uptake brought net Lys uptake close into balance with milk Lys secretion. The present data suggests that when Lys is in excess of requirements, the mammary gland appears to dispose of the extra supply via the oxidative mechanism.     

Prion‐associated proteins in yeast: comparative analysis of isogenic [PSI+] and [psi−] strains

A large group of prion‐associated proteins was identified in yeast cells using a new approach, comparative analysis of pellet proteins of crude cell lysates in isogenic strains of Saccharomyces cerevisiae differing by their prion composition. Two‐dimensional (2D) electrophoresis followed by MALDI analysis of the pellet proteins of [PSI⁺] and [psi^?] strains after prion elimination by GuHCl and prion transmission by cytoduction permitted identification of ca. 40 proteins whose aggregation state correlated with the change of prion(s) content. Approximately half of these proteins belonged to chaperones and to enzymes of glucose metabolism. Chaperones are known to be involved in prion metabolism and are expected to be present in prion‐containing aggregates, but glucose metabolism enzymes are not predicted to be present. Nevertheless, several recent data suggest that their presence is not incidental. We detected six proteins involved in oxidative stress response and eight in translation. Also notable is a protease. Most of the identified proteins seem to be prion‐associated, but we cannot exclude the possibility that several proteins may propagate as prions. Copyright © 2009 John Wiley & Sons, Ltd.