scholarly journals Digestion of the zinc in human milk, cow's milk and a commercial babyfood: some implications for human infant nutrition

1986 ◽  
Vol 55 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Peter Blakeborough ◽  
Michael I. Gurr ◽  
Dallyn N. Salter
Keyword(s):  
Molecular Weight ◽  
Human Milk ◽  
High Molecular Weight ◽  
Stomach Contents ◽  
Human Infant ◽  
Soluble Form ◽  
Cow’S Milk ◽  
Low Molecular Weight ◽  
Cow's Milk ◽  
Molecular Weight Form

1. The digestion of zinc present in human milk, cow's milk and a commercial babyfood was compared, using the piglet as a model for the human infant.2. In piglets given human milk the pH of stomach contents was approximately 1 and 0.4 units lower than that of animals given respectively cow's milk and babyfood. The pH values of intestinal contents were approximately neutral and did not vary with the type of feed.3. Hard casein curds were present throughout the stomachs and small intestines of animals fed on cow's milk or babyfood and between 55 and 70% Zn in these digesta samples were recovered in an insoluble form by centrifugation. In contrast, little solid material was observed in the digesta of animals fed on human milk, and 57 and 93% respectively of the Zn in digesta were recovered in a soluble form in the stomach and small intestine.4. Soluble fractions prepared by centrifugation of digesta were analysed by filtration on Sephadex G-150. After any of the three feeds, soluble Zn in stomach contents was mainly in a low-molecular-weight form. In intestinal samples, however, Zn was present in low- and high-molecular-weight forms. Whilst there were similar amounts of Zn in the low-molecular-weight form in all samples, approximately three times as much of the total intestinal Zn was in a soluble high-molecular-weight form complexed to proteins in the animals fed on human milk compared with those fed on cow's milk or babyfood.5. Analysis of protein-bound soluble Zn in intestinal samples on SDS-polyacrylamide gels resulted in a similar pattern of proteins for all feeds. Results indicated that at least some of these proteins were derived from intestinal secretions of the piglet.6. Some implications of these results in respect of the mode of digestion of Zn and its biological availability to the human infant are discussed.

scholarly journals Zinc binding in cow's milk and human milk

1983 ◽  
Vol 209 (2) ◽  
pp. 505-512 ◽  
Author(s):  
P Blakeborough ◽  
D N Salter ◽  
M I Gurr
Keyword(s):  
Molecular Weight ◽  
Human Milk ◽  
Average Molecular Weight ◽  
Human Infant ◽  
Zinc Binding ◽  
Cow’S Milk ◽  
Major Protein ◽  
Cow's Milk ◽  
Beta Casein ◽  
A Minor

In both cow's milk and human milk, zinc was associated with proteins of high molecular weight (greater than 100 000), as judged by analysis with Sephadex G-75. Precipitation of the casein at pH 4.6 and filtration of the resultant acid whey on Sephadex G-25 led, however, to the recovery of about 90% of the zinc as a compound of low molecular weight, which was tentatively identified as zinc citrate. Over 95% of the zinc of cow's milk was sedimented with the casein micelles on ultracentrifugation. Filtration of these micellar caseins on Sephadex G-150 gave two peaks containing zinc, which corresponded to aggregates of alpha-casein-kappa-casein and of alpha-casein-beta-casein. Ultracentrifugation of human milk sedimented only approx. 40% of total zinc. Analysis of sediment and supernatant on Sephadex G-150, however, indicated that about 85% of the zinc was associated with a protein complex of molecular weight greater than 150 000. The major protein of this complex was identified as lactoferrin. A minor zinc-binding component of average molecular weight 30 000 was also observed in the supernatant. The results indicated that zinc is bound to different macromolecules in cow's and human milk. This may be a factor affecting the bioavailability to the human infant of zinc from the two milks, and it is suggested that in human milk lactoferrin may be involved in the uptake of zinc.

scholarly journals The interrelations between high- and low-molecular-weight forms of normal and mutant (Krabbe-disease) galactocerebrosidase

1980 ◽  
Vol 189 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Yoav Ben-Yoseph ◽  
Melinda Hungerford ◽  
Henry L. Nadler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Krabbe Disease ◽  
Low Molecular Weight ◽  
Molecular Weight Form

Galactocerebrosidase (β-d-galactosyl-N-acylsphingosine galactohydrolase; EC 3.2.1.46) activity of brain and liver preparations from normal individuals and patients with Krabbe disease (globoid-cell leukodystrophy) have been separated by gel filtration into four different molecular-weight forms. The apparent mol.wts. were 760000±34000 and 121000±10000 for the high- and low-molecular-weight forms (peaks I and IV respectively) and 499000±22000 (mean±s.d.) and 256000±12000 for the intermediate forms (peaks II and III respectively). On examination by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the high- and low-molecular-weight forms revealed a single protein band with a similar mobility corresponding to a mol.wt. of about 125000. Antigenic identity was demonstrated between the various molecular-weight forms of the normal and the mutant galactocerebrosidases by using antisera against either the high- or the low-molecular-weight enzymes. The high-molecular-weight form of galactocerebrosidase was found to possess higher specific activity toward natural substrates when compared with the low-molecular-weight form. It is suggested that the high-molecular-weight enzyme is the active form in vivo and an aggregation process that proceeds from a monomer (mol.wt. approx. 125000) to a dimer (mol.wt. approx. 250000) and from the dimer to either a tetramer (mol.wt. approx. 500000) or a hexamer (mol.wt. approx. 750000) takes place in normal as well as in Krabbe-disease tissues.

Immunoaffinity Chromatography of Canine High-Molecular-Weight Renin: Partial Purification and Characterization

1983 ◽  
Vol 65 (2) ◽  
pp. 117-120 ◽  
Author(s):  
Fumihiko Ikemoto ◽  
Victor J. Dzau ◽  
Edgar Haber ◽  
Kazuo Takaori ◽  
Kenjiro Yamamoto
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Specific Activity ◽  
Immunoaffinity Chromatography ◽  
Partial Purification ◽  
Low Molecular Weight ◽  
Specific Method ◽  
Disulphide Bonds ◽  
Binding Substance ◽  
Molecular Weight Form

1. Canine high-molecular-weight renin (mol. wt. 60 000) is believed to be a complex of renin (low-molecular-weight form, mol. wt. 40 000) and renin-binding substance. The immunocross-reactivity of high-molecular-weight renin and low-molecular-weight renin was demonstrated by using antibodies specific to low-molecular-weight renin. 2. Immunoaffinity chromatography with renin-specific antibodies coupled to Sepharose provided a simple and specific method for isolation of high-molecular-weight renin. High-molecular-weight renin with a specific activity of 137 600 ng of ANG I h−1 mg−1 of protein (19.6 Goldblatt units/mg of protein) was obtained. 3. This high-molecular-weight renin was stable in dithiothreitol (25 mmol/l), suggesting that disulphide bonds may not be involved in the binding mechanism between low-molecular-weight renin and renin-binding substance. 4. However, exposure to low pH (3.0) resulted in conversion of high-molecular-weight renin into the low-molecular-weight form.

Conditions Affecting the Molecular Weight of Factor VIII.

1979 ◽  
Author(s):  
G. Rock ◽  
E. Tackaberry ◽  
D. Palmer
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
High Molecular Weight ◽  
Calcium Concentration ◽  
Low Molecular Weight ◽  
Biochemical Purification ◽  
Molecular Weights ◽  
Will Self ◽  
And Storage ◽  
Molecular Weight Form

By purifying Factor VIII while maintaining physiological concentrations of calcium we have recently demonstrated that about 50% of the procoagulant activity is in a very low molecular weight (VLHW) form not associated with the carrier (VIII: RAG). The remainder is carrier associated and elutes at Vo as a high molecular weight (HMW) compound upon Sepharose 6B chromatography. Reduction of the calcium concentration by increasing the amount of citrate added to heparin results in decreasing the ratio of VLMW:HMW from 1:1 in pure heparin to 1:5 in pure citrate. If citrate is replaced with the more strongly chelating EDTA no VLMW is detectable in the plasma. It has also been found that most of the biochemical purification techniques which have been previously used to prepare Factor VIII for study actually result in the aggregation of this VLMW with the carrier to produce the high molecular weight form. This includes: cryoprecipitation, precipitation by polyethylene glycol and storage -80°C. As well, the VLMW material will self-associate upon freezing to produce an aggregate with a molecular weight of 106. However, this material does not cross-react with rabbit antibody directed against VIII: RAG. The data indicate that many of the previously reported biochemical characteristics, including molecular weights, actually describe species which are artifacts of the isolation process rather than those of the physiologically occuring Factor VIII.

ETIOLOGIC FACTORS IN TETANY OF NEWLY BORN INFANTS

PEDIATRICS ◽  
1950 ◽  
Vol 5 (2) ◽  
pp. 228-240
Author(s):  
LYTT I. GARDNER ◽  
ELSIE A. MACLACHLAN ◽  
WALTER PICK ◽  
MARY L. TERRY ◽  
ALLAN M. BUTLER
Keyword(s):  
Breast Milk ◽  
Human Milk ◽  
Newborn Infant ◽  
Neonatal Period ◽  
Elevated Serum ◽  
Human Infant ◽  
Cow’S Milk ◽  
Milk Formula ◽  
Cow's Milk ◽  
Ca:P Ratio

Sixteen cases of neonatal tetany are reported, all of whom were fed cow's milk formulas. Relative to human milk, cow's milk has a low Ca:P ratio and increased total P concentration. These differences are accentuated in some commercial milks prepared for infant feeding. Cow's milk, even if diluted 2:1 with water, is an unphysiologic food for the human infant in the neonatal period, producing elevated serum P and decreased serum Ca and Mg levels. Increasing the Ca:P ratio of cow's milk to that of human milk or dilution 1:2 with water limits the abnormal changes in serum P, Ca and Mg concentrations referred to. A high P diet of an inadequately diluted cow's milk formula causes hypertrophy of the parathyroid glands of the newborn infant. The maximum renal P clearance of the human newborn infant in the first week of life appears to approximate 3500 ml./sq. m./24 hrs. Our observations indicate that when newborn infants are fed cow's milk formulas commonly used in this country limitation in parathyroid and renal function predisposes to tetany. The foregoing data emphasize the physiologic character of human milk for the newborn infant. If breast milk is unavailable, a suitable formula for the neonatal period appears to be cow's milk 1 part, water 2 parts, 10% carbohydrate and Ca-gluconate to produce a Ca:P ration approaching that of breast milk. The added water and Ca should then be gradually reduced.

scholarly journals Conversion of low molecular weight renin into the high molecular weight form by Cu2+ in the rat kidney.

1984 ◽  
Vol 7 (11) ◽  
pp. 820-829
Author(s):  
SHIRO MORIMOTO ◽  
KATSUJHIKO ITO ◽  
TAKAHIRO IWAMOTO ◽  
YUKA KOSEDA ◽  
MASANORI TAKAOKA
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Rat Kidney ◽  
Low Molecular Weight ◽  
High Molecular Weight Form ◽  
Molecular Weight Form

Liquid Rubbers—General Rubber Products Technology

1971 ◽  
Vol 44 (3) ◽  
pp. 750-757 ◽  
Author(s):  
J. R. Pyne
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Raw Material ◽  
Development Work ◽  
Low Molecular Weight ◽  
Scale Production ◽  
Theoretical Possibility ◽  
High Molecular Weight Form ◽  
End Groups ◽  
Molecular Weight Form

Abstract Mixing and processing methods used in the rubber industry have been designed to use the only form of raw rubber hitherto available—that of a high molecular weight solid. But rubber in high molecular weight form is essential only in the finished product; in principle, similar final properties could be obtained from a low molecular weight raw material provided this could be chain extended before or during the final shaping and vulcanizing operation. This approach has been employed for some time in the rather specialized field of castable polyurethane rubber manufacture. Its exploitation for more general rubber manufacture has become more than just a theoretical possibility with the recent availability of “liquid rubbers” whose molecules have reactive end groups. Those available at present may well prove not fully acceptable, either economically or technically, but it is most unlikely that they represent the best that can be achieved. Material developments will be encouraged if means have been worked out for exploiting liquid rubbers' potential advantages (such as the ability to be processed on lighter and less powerful equipment), and the shortcomings of existing examples have been identified. These considerations led RAPRA to start a processing and compounding study—a decision which seems further justified by the very recent American announcements of development work on a tire manufacturing process using liquid rubber, and of full commerical scale production of several hydroxyl terminated liquid butadiene polymers. This report summarizes the study to date.

Purification of High Molecular Weight Urokinase from Human Urine and Comparative Study of Two Active Forms of Urokinase

1983 ◽  
Vol 49 (02) ◽  
pp. 091-095 ◽  
Author(s):  
Takeji Shibatani ◽  
Toshio Kakimoto ◽  
Ichiro Chibata
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Low Molecular Weight ◽  
Improved Method ◽  
Assay Methods ◽  
Hydroxyl Apatite ◽  
Cellulose Column ◽  
Molecular Weight Form

SummaryAn improved method for the purification of high molecular weight urokinase to homogeneity from human urine was established. A yield of 32% with a 3,100-fold purification was obtained by Hyflo Super-Cel treatment, heat treatment at 60° C for 10 hr, serial column chromatography on DEAE-Sepharose CL-6B and 0-[3-(p-sulfophenylamino)-2-hydroxypropyl]-cellulose (SFOP-cellulose), and gel filtration on Ultrogel AcA 54. The low molecular weight form of urokinase was also purified to homogeneity by chromatography on hydroxyl apatite and gel filtration on Sephadex G-75 after the SFOP-cellulose column step. The high molecular weight urokinase had only one isoelectric form with a pi of 9.7, whereas the low molecular weight form had six isoelectric subforms with pi values between 9.4 and 6.4. The absorption coefficients at 280 nm of both urokinase forms were 13.61 and 13.50, respectively. Fibrinolytic and esterolytic activities of the two urokinase forms were compared in various assay methods.

scholarly journals Thermal Instability of the Trimeric Structure of the N-terminal Propeptide of Human Procollagen Type I in Relation to Assay Technology

1999 ◽  
Vol 45 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Jette Brandt ◽  
Thomas N Krogh ◽  
Charlotte H Jensen ◽  
Jette K Frederiksen ◽  
Børge Teisner
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Type I ◽  
Thermal Transition ◽  
Procollagen Type ◽  
High Molecular Weight Form ◽  
Procollagen Type I ◽  
Trimeric Structure ◽  
Molecular Weight Form

Abstract The N-terminal propeptide of procollagen type I (PINP) appeared in two peaks after size chromatography. The high-molecular weight form was transformed to the low-molecular weight form during incubation at 37 °C, whereas the low-molecular weight form remained unchanged. The PINP concentrations in amniotic fluid and sera remained unchanged during 37 °C incubation when measured using an ELISA; however, concentrations decreased by 89–93% when measured using an RIA. The ELISA:RIA ratio varied from 1.1 to 2.9 in these fluids because of different size distributions and the inability of the RIA to measure the low-molecular weight form. Thermal transition of the high-molecular weight form caused a change in its elution volume but did not change its migration in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Mass spectrometry revealed identical results for both forms. We reached the following conclusions: (a) the trimeric structure of PINP is unstable at 37 °C; (b) the two molecular forms represent intact α1 chains in trimeric and monomeric forms; (c) thermal transition is an ongoing in vivo process; and (d) this is important in the choice of assay technology.

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