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Biomedical subjects

H M Farrell

Publications and source records attributed to H M Farrell.

At least 73 records · Page 4Linked to original sources
PubMed1987

Role of the isocitrate dehydrogenases and other Krebs cycle enzymes in lactating bovine mammary gland.

The role of the isocitrate dehydrogenases and other Krebs cycle enzymes in bovine mammary metabolism was studied by investigation of their distribution between cytosol and mitochondria. Citrate synthase was used as a marker for mitochondrial disruption, and distributions were normalized to this enzyme. Aconitase, fumarase, and NAD+:malate dehydrogenase were distributed between the mitochondria and the cytosol; evidence for the possible involvement of an aspartate:malate shuttle was also found. The NADP+:isocitrate dehydrogenase is predominantly cytosolic with a small but significant amount of mitochondrial component. Using the dye dichlorophenol-indophenol, a low level of NAD+:isocitrate dehydrogenase activity was observed in bovine mammary tissues. This assay also allows for detection of the enzyme in fresh mitochondria from a variety of other bovine tissues (heart, liver, kidney, and brain). Activities of the isocitrate dehydrogenases were also examined as a function of gestation and lactation. The NAD+:isocitrate dehydrogenase is apparently depressed during gestation with the NADP+ form of the enzyme (cytosolic) elevated postpartum. These results indicate that a substantial portion of Krebs cycle activity may become extramitochondrial in bovine mammary gland at the onset of lactation.

Animals↗
PubMed1987

Absence of detectable calmodulin in cows' milk by a modified gel electrophoresis method.

With a simple, sensitive, and rapid SDS-PAGE procedure, developed during the course of this study, calmodulin was not found in cows' milk. The absence of calmodulin at the level of detection provided by this procedure (.4 micrograms) was unexpected. Because milk is a repository for many protein and enzyme systems, and because the mammary gland is known to contain calmodulin, it was conjectured that at least some "leakage" of the protein into milk would occur, especially into colostrum.

Animals↗
PubMed1987

Isolation and characterization of bovine mammary calmodulin.

Bovine mammary gland calmodulin, purified by conventional fractionation procedures, was compared with similarly purified bovine brain calmodulin. Affinity chromatography on W-7 agarose of the crude fractions from mammary gland and brain yielded pure proteins containing one trimethyllysine residue per 16,800 daltons with essentially identical amino acid compositions. Kinetic parameters of these two proteins with respect to their ability to activate phosphodiesterase were determined. The constants for half maximum activation were .39 and .44 nM for bovine brain and bovine mammary gland calmodulins, respectively; both proteins gave similar maximum velocities. Based on the amino acid composition and kinetic data, it is concluded that the two proteins are essentially identical.

Amino Acids↗
PubMed1986

Comparative study of the molecular species of chloropropanediol diesters and triacylglycerols in milk fat.

In an effort to establish the origin of the fatty acid esters of 3-chloropropanediol, which recently have been isolated in small amounts from goat milk, we compared the molecular species composition of the chlorohydrin diesters and of goat milk triacylglycerols. The chloropropanediol diesters were found to be composed of molecular species containing C10-C18 fatty acids and corresponded closely in carbon number to those calculated for the long chain sn-1,2-diacylglycerol moieties of goat milk triacylglycerols. The molecular species of goat milk total triacylglycerols contained C4-C18 fatty acids. It is suggested that triacylglycerols and chloropropanediol diesters are derived from the same pool of long chain fatty acids. A molecular distillate of bovine milk fat did not contain chloropropanediol diesters, while the available samples of human milk fat were shown to contain alkyldiacylglycerols as the major components of a neutral lipid fraction corresponding in polarity to the chloropropanediol diesters.

Animals↗
PubMed1986

Radioimmunoassay for measurement of bovine alpha-lactalbumin in serum, milk and tissue culture media.

A sensitive, specific radioimmunoassay for bovine alpha-lactalbumin (alpha-la) suitable for measurement of serum, tissue culture media and milk was developed. alpha-La was not detected in serum from prepubertal male or female cattle, but was detected as early as 60 d of gestation in nulliparous Holstein heifers, the level being greatly increased during the last one third of gestation. Serum from cross bred beef heifers contained less alpha-la and it was not detected until late gestation. Concentrations of alpha-la in serum samples from pregnant multiparous Holstein cows decreased at drying-off and subsequently increased just before parturition. Secretion of alpha-la by mammary tissue explants from steroid-primed prepubertal Holstein heifers was induced by the addition of bovine prolactin, ovine prolactin or human growth hormone to tissue culture media.

Anestrus↗
PubMed1985

Ectrodactyly in central Africa.

Autosomal dominant ectrodactyly has been identified in several families in remote areas of central Africa. Two groups from eastern Botswana and south-western Zimbabwe belong to the Talaunda tribe and have a common ancestral origin. Another family are members of the Wadoma tribe of north-eastern Zimbabwe. A total of 24 individuals may be affected. Tenuous historical evidence suggests that the Talaunda migrated from the eastern Zambezi region late in the last century and may have the same origins as the Wadoma tribe. On this basis it is likely that the affected people have the same faulty gene, which presumably arose by mutation in a common progenitor.

Adolescent↗
PubMed1985

Identification of the milk fat globule membrane proteins. II. Isolation of major proteins from electrophoretic gels and comparison of their amino acid compositions.

The fat globule membranes of milk are derived from the apical plasma membrane of the mammary secretory cells. The nature of the membrane proteins, as isolated from cows' milk, has been studied by the use of discontinuous and continuous SDS-gel electrophoresis. Six methods of preparation of milk fat globule membrane suggested by various authors were tested; gel electrophoresis showed that five major bands were present, independent of the method of preparation. The apparent molecular masses of these proteins as determined on SDS-gels (15% T) were 167, 142, 64, 49 and 46 kDa, respectively. The 167 kDa band stained only with periodic acid-Schiff reagent, while the 142 kDa band stained only with Coomassie blue; the last three bands stained with both. Delipidated membranes were extracted stepwise with water, 0.02 M NaCl and 0.6 M NaCl. The 64 kDa band appears to be nearly insoluble, while the bands of 142, 49 and 46 kDa are fractionated by this procedure. The resolution of all of these proteins by electrophoresis was superior to that achieved by molecular sieve chromatography, and so electrophoretic extraction was used to isolate the major proteins. Dansyl chloride derived proteins were used as markers. Amino acid compositions of the recovered proteins were obtained and are compared.

Amino Acids↗
PubMed1985

Isolation and characterization of new proteins produced by the infusion of colchicine in goat mammary gland.

Three new proteins have now been isolated from goat milk obtained after colchicine is infused into the mammary gland. Two of the proteins are proline-rich, and a third is a very acidic phosphoprotein. One of the proline-rich proteins is related compositionally to a sheep colostrum proline-rich protein, which has been shown to have a regulatory effect on the immune response (Janusz, M., Stavoscik, K., Zimecki, M., Wieczorek, Z., and Lisowski, J. (1981) Biochem. J. 199, 9-15). Other aspects of colchicine-treated milks are described.

Amino Acids↗
PubMed1985

Spectrophotometric estimation of protein concentration in the presence of tryptophan modified by 2-hydroxy-5-nitrobenzyl bromide.

A spectrophotometric method makes it possible to determine the concentration of a protein after covalent modification of tryptophan residues by 2-hydroxy-5-nitrobenzyl bromide. Molar absorption coefficients for the 2-hydroxy-5-nitrobenzyl chromophore, reported here in the pH range from 4.0 to 10.9, can be used to correct the protein absorbance values at 280 nm, which then provides the basis for calculating protein concentration in the usual way. The method was tested with alpha-lactalbumin, beta-lactoglobulin, pepsin, and soybean trypsin inhibitor; spectrophotometrically estimated concentrations of these proteins agreed closely with values obtained by amino acid analysis.

2-Hydroxy-5-nitrobenzyl Bromide↗
PubMed1985

Isolation and properties of goat beta 2-microglobulin.

Goat beta 2-microglobulin was isolated and purified from colostrum. Comparisons of the amino acid composition and amino-terminal sequence of the goat protein with the bovine and human homologues, indicates a high degree of similarity. Both goat and bovine beta 2-microglobulins differ slightly in composition from the human molecule, most notably in threonine and proline values. For the first 32 residues, bovine and goat differ only at two positions, one of which is a valyl/isoleucyl substitution consistent with the amino acid compositions. The equivalent goat/human sequence comparison shows seven differences. Immunological studies, using the ELISA method, also confirm the close relatedness of goat and bovine beta 2-microglobulin and their more distant relatedness to the human homologue.

Amino Acid Sequence↗
PubMed1985

Composition of the hydrocarbon fraction of goats' milk.

The hydrocarbon fraction of the neutral lipids of goats' milk was chromatographically purified and analyzed by gas-liquid chromatography and mass spectrometry. The goats' milk samples, which were collected during the spring of the year, represent a cross-sectional analysis; the purified hydrocarbon fraction displays a broad spectrum of compounds. The major components of the hydrocarbon fraction identified for the first time in goats' milk were 3,7,11,15-tetramethylhexadec-2-ene (phytene-2) (1.5%), squalene (approximately 2.5%), and n-C29H60 (4.2%); in addition, a series of odd and even carbon number n-alkanes (C15 to C33), a series of alkenes (C16 to C23), and a series of branched chain hydrocarbons were found. The goats' milk hydrocarbon fraction, in comparison to the known distribution from cows' milk, contains a good deal less squalene and phytene, and is more complex. One human milk hydrocarbon fraction isolated from a longitudinal composite sample from one lactation displays a distribution that appears to be more closely related to that of human skin lipids (1983. J. Lipid Res. 24: 120-130) than to those of goats' and cows' milk.

Animals↗
PubMed1983

Fatty acid composition of polar lipids in goats' milk.

Silicic acid column chromatography was used to separate the polar lipids of goats' milk into glycolipid, phosphatidylethanolamine, phosphatidylserine plus phosphatidylinositol, phosphatidylcholine, and sphingomyelin fractions. Each fraction was purified by column chromatography and its fatty acid profile determined by gas liquid chromatography and mass spectrometry. The glycerophospholipids each contained 18:1 as the predominant fatty acid (approximately 45%). The sphingolipids contained a high percentage of long-chain saturated fatty acids (C22 to C24 greater than 45%); the glycolipid fraction also contained ca. 2% 2-hydroxy fatty acids. The data represent a comprehensive cross-sectional study of the major polar lipids found in goats' milks.

Animals↗
PubMed1982

Isolation and solubilization of casein kinase from Golgi apparatus of bovine mammary gland and phosphorylation of peptides.

Phosphate incorporation from [gamma-32P]ATP into native and dephosphorylated alpha s1-casein is catalyzed by a casein kinase localized in the Golgi apparatus of lactating bovine mammary gland. Casein kinase from the Golgi is activated with either Mg2+ or Ca2+, and increased specific activity is observed with dephosphorylated casein as the substrate. The casein kinase can be solubilized from Golgi apparatus by the non-ionic detergent, Triton X-100. Gel permeation chromatography on Sepharose CL-4B yields a Stokes radius of 10 nm for the detergent-solubilized casein kinase. Dephosphorylated beta-peptide, the amino-terminal peptide from beta-casein, is a good substrate for the solubilized casein kinase. With dephosphorylated beta-peptide, the maximal velocity is 9.1 and 12.0 nmol/min per mg protein with Mg2+ and Ca2+ activation, respectively. The Michaelis constant for beta-peptide is greater with Ca2+ than with Mg2+ (4.8 mg/ml compared to 0.97 mg/ml). However, the Michaelis constant for ATP is not greatly influenced by these metal ions. The Triton X-100-solubilized Golgi enzyme can also catalyze the phosphorylation of peptides, such as fibrinopeptide A and alpha-melanocyte stimulating hormone.

Animals↗
PubMed1979

Charge separation of proteins complexed with sodium dodecyl sulfate by acid gel electrophoresis in the presence of cetyltrimethylammonium bromide.

Globular proteins, casein, and membrane proteins which were reacted with sodium dodecyl sulfate were studied by acid urea gel electrophoresis. The sodium dodecyl sulfate bound tightly to the proteins, producing a more acidic charge which prevented migration into the gel. When cetyltrimethylammonium bromide was added to the sodium dodecyl sulfate-protein complexes, the sodium dodecyl sulfate apparently reacted with cetyltrimethylammonium bromide and dissociated so that the proteins migrated in acid gel in a normal manner as compared to the proteins without any added detergent. The sodium dodecyl sulfate-cetyltrimethylammonium bromide complex could be removed from the proteins by centrifugation. Thus, cetyltrimethylammonium bromide used in conjunction with acid gel electrophoresis allows direct comparison by charge of proteins fractionated in the presence of sodium dodecyl sulfate with the starting mixture of proteins not exposed to detergent. The reaction of cetyltrimethylammonium bromide with sodium dodecyl sulfate in acidic urea also provides a simple convenient method of removal of sodium dodecyl sulfate from proteins.

Cetrimonium Compounds↗